The applicants say that the EPA should regulate the emissions under the Clean Air Act because they are air pollutants which could harm public health.

The EPA said it cannot regulate global warming under the act, and therefore carbon dioxide, as a greenhouses gas, is not an air pollutant.

The agency also said it would not regulate such gases, even if it could, because there is uncertainty about global warming.

The government position is supported by car-industry groups and nine states where vehicles are made.

The applicants took their case to the top court after the EPA refused an environmental group's request to regulate emissions. A lower court in Washington, D.C., backed the EPA.

The Supreme Court is expected to rule by July 2007.

The court is also hearing a second, related case regarding an EPA decision that it lacked the authority to regulate greenhouse-gas emissions from power plants.

The study used functional magnetic resonance imaging to record tiny metabolic changes in brain activity in 44 adolescents who were asked to perform a series of tasks after playing either a violent or nonviolent video game for 30 minutes.

The children, with no history of behavior problems, ranged in age from 13 to 17. Half played a T-rated (for Teen) first-person shooter game called Medal of Honour: Frontline, involving military combat, while the other group played a nonviolent game called Need for Speed: Underground.

Those who played the violent video game showed more activation in the amygdala, which is involved in emotional arousal, and less activation in the prefrontal portions of the brain associated with control, focus and concentration than the teens who played the nonviolent game.

"Our study suggests that playing a certain type of violent video game may have different short-term effects on brain function than playing a nonviolent, but exciting, game," said Vincent Mathews, a professor of radiology at Indiana University School of Medicine in Indianapolis and the study's author.

The findings were presented at a meeting of the Radiological Society of North America. The 13 billion dollars U.S. video game industry, with revenue rivaling Hollywood box office sales, is at the center of a cultural battle over violent content.

Lawmakers' various attempts to ban the sale of violent video games to children have been blocked by courts in Louisiana, Illinois, California. Michigan and Minnesota.

In his January 2003 State of the Union address, President George W. Bush announced a $15 billion initiative to "turn the tide" against AIDS, targeted mainly at 14 of the hardest-hit African and Caribbean countries, plus Vietnam. That would virtually triple the U.S. commitment, offering renewed hope to the nearly 30 million AIDS sufferers in Africa alone.

It all sounded grand.

But very quickly, the strings of the plan -- now known as PEPFAR, the President's Emergency Plan for AIDS Relief -- began to show. Starting in 2004, the United States recommended -- and by 2006 required -- that 33 percent of all prevention funding be earmarked for abstinence and fidelity programs. Condoms could be recommended only for high-risk groups, not for sexually active people in general. No funds would be provided to groups that don't explicitly condemn prostitution. Finally, the Bush administration seemed to be spreading a significant share of AIDS funding through faith-based groups.

Meanwhile, the AIDS pandemic has been rapidly feminized over the past 15 years. But PEPFAR -- underpinned by the political and religious philosophies of the Bush administration -- often doesn't take into account the facts of life for women in the countries it serves.

"The gender dimensions of the epidemic are completely ignored," says Beatrice Were, a Ugandan mother of three who has devoted herself to AIDS activism since 1993. "We know very well that women don't [always] have control [over sexual decisions]. There is rape in marriage. ... Many women can't make a decision on whether to have protected sex or not, even whether to have sex or not, because it's their husbands [who] make the decision."

In Uganda polygamy and promiscuity among men is both significant and socially acceptable. "This [PEPFAR] approach places a huge burden on a woman to abstain and, when she's married, be faithful," says Were. "Personally, I did all of that, but I still got infected, too. It just doesn't work."

Nonetheless, the ABC plan -- Abstinence, Be faithful and use Condoms -- continues to be the preferred U.S. strategy for preventing sexually transmitted HIV infections. Indeed, service providers often have to reduce other programs -- such as those to prevent mother-to-child HIV transmission -- in order to redirect dollars toward abstinence and thus meet the 33 percent requirement.

But an abstinence-only approach has not proven effective in preventing AIDS transmission; in fact, it may have an opposite effect. In Uganda, which successfully promoted a comprehensive program before PEPFAR, the incidence of the virus has nearly doubled since shifting its focus to comply with PEPFAR's A and B guidelines. When first recognized in the early 1980s, AIDS was pegged as a disease affecting primarily men, homosexuals, Haitians or intravenous-drug-users. But over the years, HIV has increasingly infected women who are married, have children and are nonwhite and poor. Today, 17.3 million women in the world live with HIV/AIDS, and of the 16,000 new HIV infections daily, as many as 55 percent occur among women. The proportion of women among the total infected population has risen at a steady and frightening rate: from 35 percent in 1990 to 41 percent in 1997, to 48 percent in 2004.

The women of sub-Saharan Africa are particularly hard-hit. They comprise 54 percent of all HIV/AIDS cases in the region, and three of four newly infected young people (15 to 24 years old) are women.

A number of studies have found that male-to-female transmission of HIV during sex is about twice as likely to occur as female-to-male transmission, because the HIV virus can more easily penetrate vaginal mucus during intercourse. The risk runs even higher if intercourse is violent, as abrasions caused by forced penetration facilitate entry of the virus -- which puts adolescent girls at increased risk. As Stephen Lewis, U.N. Special Envoy for HIV/AIDS in Africa, pointed out at the 2006 International AIDS Conference in Toronto, "In Africa... the violence and the virus go together."

The risk of sexual violence and rape should therefore be a crucial component in HIV-prevention policies, says the Rev. Mpho Tutu, daughter of South African Archbishop Desmond Tutu and an Episcopal priest in Alexandria, Va. "One of the reasons for the feminization of the pandemic is the instability of war and displacement," she explains. "Refugee women are vulnerable because rape and sexual exploitation are weapons of war.... And as communities are destabilized, more and more often you'll see women trading sexual favors for economic support."

Sex-for-survival can also occur in the home, especially when women are poor, as they are in great swatches of the PEPFAR countries. As for using condoms, studies in Haiti, another PEPFAR focus country, show that more than 60 percent of Haitian women feel that the decision about whether to use condoms is exclusively the man's right. Discussion of safe sex, as suggested by the ABC plan, requires a discussion of sex itself. Yet the PEPFAR policy is to restrict comprehensive sexual-education programs to only certain sectors of the population. Children up to age 14, for example, are not to be introduced to condoms in any PEPFAR- funded school programs. Unmarried youth are often taught only about abstinence and being faithful. This policy does not reflect the reality of Haitians' sex lives, of course: Recent surveys show that 60 percent of young males and 36 percent of young females reported having their first sexual contact before 15 years of age.

Even when condoms are offered by health providers, U.S. requirements stipulate that they must always be accompanied by a notice of their failure rates. Says HIV/AIDS consultant David Veazey, "This is not something you would put in a campaign slogan to promote condoms. It would be the same as a seat-belt commercial saying, 'Buckle Up! But there is a 10 percent chance that the seat belt won't save you in an accident.' Not only would people continue to drive -- because they have to -- but they probably wouldn't see the point in wearing a seat belt either."

The U.S. has recognized that the ABC policy isn't always appropriate, so it has allowed some of the PEPFAR "teams" within the focus countries to direct less of their programs to abstinence and fidelity. But then the rest of the countries' provider teams have to spend more on A and B, which means cutting back on other programs.

"We continue to act as if poor people are stupid people," says Rev. Tutu. "They aren't stupid, they're just poor. They are entitled to make full decisions. [If you provide ABC] and [say] that's all that's available, it's dishonest and it infantilizes those to whom we provide the message."

PEPFAR isn't the only source of significant global funding on AIDS, just the biggest. But its prevention guidelines are quite different from those of another significant player, the Global Fund to Fight AIDS, Tuberculosis and Malaria. The internationally supported Fund, started in 2002, is not required to follow the ABC policy, although its resources are fewer than those of PEPFAR.

"I think the position of PEPFAR is guided by some religious aspect," says Dr. Émile Charles, head of a Global fund-sponsored health program in Haiti. "But it's important ... for a country like Haiti ... to continue to focus on condoms. I think that promoting abstinence is an error, a scientific error."

Restrictive U.S. guidelines have caused some countries and providers to refuse its funding. Brazil turned down $40 million in U.S. AIDS funding in 2005 because it refuses to take a required pledge against "the legalization or the practice of prostitution" (which is already decriminalized in Brazil). The country's AIDS program, considered among the world's most progressive, counts its commercial sex workers among its most determined AIDS activists. Other AIDS providers are reluctant to sign the pledge because they don't want to increase the stigma and isolation of sex workers, which would thus raise further barriers to getting them needed HIV services.

Congress has recently begun to weigh in on PEPFAR: The bipartisan Protection Against Transmission of HIV for Women and Youth Act of 2006 (PATHWAY), announced in June, would require the program's administrators to establish a prevention strategy that addresses the vulnerabilities of women and girls to HIV, eliminates the funding earmark for abstinence, increases access to male and female condoms and addresses gender violence as a cause of HIV/AIDS.

"A growing number of Congress members agree that this bill is important, as it continues to attract new cosponsors from both parties every month," says Jodi Jacobson, director of the Center for Health and Gender Equity, a nonprofit that advocates accountability for U.S. health policies abroad. "PATHWAY...forces the hand of the administration ... to do the right thing when constructing a truly comprehensive approach to prevention.

"We should pass it tomorrow."

Sarah Fort is a writer for the Center for Public Integrity. She works with the center's international project.

Thank goodness these secretive, corporate drug trials are counterbalanced by taxpayer-funded studies at the National Institutes of Health (NIH), whose results are open to public scrutiny, right?

Actually, wrong.

You would think that, because taxpayers paid for the studies, the data ought to be available for independent verification. But that's not how it actually works.

When several leading researchers contacted me, frustrated because they couldn't obtain data from NIH-funded studies, I filed Freedom of Information Act (FOIA) requests for the data they were unable to obtain.

My FOIA requests were denied.

Indeed, despite a 1999 law clearly stating that such information should be available to the public, it appears that no data have ever been released under the law. And the price for that secrecy may be paid in American lives.

The use of steroids to treat spinal-cord injuries offers a sobering example. In late March 1990, the NIH announced, with great fanfare, the results of the Second National Acute Spinal Cord Injury Study (NASCIS 2), a 487-persontrial that appeared to show that high-dose steroids reduced paralysis caused by acute spinal cord injury. Underscoring the urgency of its results, the NIH issued an unprecedented prepublication press release. This was followed by a "Dear Doctor" letter, which was faxed to emergency departments across the nation, instructing physicians in the correct dosing of steroids for patients with such injuries. Given what was at stake, the NIH's actions appeared to be warranted. Each year, approximately 10,000 people, most of them young and healthy, suffer spinal-cord injuries in car accidents, falls, or shootings. If, as NASCIS 2 suggested, steroids helped prevent paralysis in these cases, it heralded a significant advance in treating people who might otherwise spend their lives on breathing machines and in wheelchairs. The "Dear Doctor" letter ensured that emergency-room physicians would make high-dose steroids the standard of care for victims of spinal-cord injuries.

But not all doctors were as enthusiastic about high-dose steroids as the NIH. Fred H. Geisler, a neurosurgeon with the Illinois Neuro-Spine Institute, had seen not only patients treated with steroids who failed to improve, but also patients who got worse and died--not from their injuries, but from the side effects of the steroids, such as overwhelming infections and gastrointestinal bleeding. Geisler was surprised by the NIH claims, but he knew enough to wait for the published paper so that he could go over the data himself. When the report was published in The New England Journal of Medicine, six weeks after the NIH announcement, it did nothing to allay his doubts. Instead of reporting on all the subjects included in the study, as is customary, the authors wrote up the outcomes on only a subset of patients.

Geisler knew the only way he could confirm his suspicions, or lay them to rest, would be to reanalyze the raw data from the study. But the lead author of NASCIS 2, Michael Bracken of the Yale School of Public Health, refused to release the study data to Geisler and to other critics despite multiple requests. After being contacted by some of these critics in 2003, I filed a formal FOIA request with the NIH for the data. The NIH directed me to Bracken and Yale, saying they did not possess the data. I then requested the data from Bracken and, separately, from Yale. Both denied my requests.

Lacking access to the data underlying the NASCIS 2 claims, most doctors feel obligated to prescribe steroids as the "standard of care." But it's a standard of which many are skeptical. On May 5, 2004, for instance, more than 1,000 neurosurgeons gathered at the annual meeting of the American Association of Neurological Surgeons in Orlando, Florida, to hear a debate between Bracken and Geisler on high-dose steroids. An electronic poll of the audience showed that, prior to the debate, only 21 percent of the neurosurgeons present believed that steroids lead to a significant improvement in outcome (compared with 48 percent who said it didn't improve outcome and 31 percent who responded "don't know"). After the debate, those who said steroids improved outcome dropped from 21 percent to 11 percent, and a mere 6 percent said it ought to be the standard of care. Nonetheless, when asked if they would personally prescribe high-dose steroids for patients with acute spinal cord injuries in the future, 60 of the surgeons present said they would. When asked why, 11 percent said they believed it improved outcome, 31 percent claimed they feared litigation, and 38 percent said there was no better alternative.

The concerns of skeptics like Geisler were recently amplified when the results of another study, known as the CRASH trial, were announced. The study compared patients with serious brain injuries who were treated with steroids with those treated with a placebo. For every 100 patients treated with steroids, three more patients died than did patients treated with the placebo. From these results, Geisler estimates that 5,000 people with spinal-cord injuries have already died from treatment with high-dose steroids--and that stopping steroid treatment could save 300 lives per year in the United States.

Nor is Geisler alone in his concerns. Karim Brohi, a British trauma surgeon at the Royal London Hospital, concurs: "Patients around the world are suffering due to the inappropriate reporting and application of this data," he says. "I believe it is highly questionable that Bracken should be refusing to release the original data given the potential associated morbidity and mortality associated with high-dose steroids." Perhaps the most surprising support for Geisler's views comes from an unexpected source: William Collins, a now-retired Yale neurosurgeon who was Bracken's co-principal investigator on NASCIS 2. Collins says he broke with Bracken and withdrew his name from the third trial in the series in protest because "[Bracken] was always trying to find something that I couldn't find"--i.e., a clinical benefit from steroid treatment.

Nor is this a unique case of taxpayer-funded research being kept hidden. In 2004, an NIH-sponsored study was reported to show that Prozac was effective in treating depressed teenagers. But the NIH and the study authors have refused to release the data in response to FOIA requests--requests, significantly, that were made while Congress and the FDA were holding hearings on the safety of antidepressants. In another NIH study, published in 2003, researchers reported that the brains of children with attention-deficit hyperactivity disorder (ADHD) were smaller than those of children who had not been diagnosed with the disorder. Critics questioned whether the problem might actually be caused by the drugs used to treat ADHD. But, when a researcher asked for the underlying data, his request was denied.

This isn't how it was supposed to be. The Shelby Amendment, passed in 1999, specifically directs federal agencies to "ensure that all data" from federally funded research are "made available to the public through the Freedom of Information Act." The NIH, in its data-sharing guide known as Circular A-110, asserts that data-sharing "is essential ... to improve human health." Although the NIH officially encourages data-sharing, adherence to the policy is voluntary. It is ultimately left to the individual researcher or research institution to decide whether or not to share their data. As Norka Ruiz-Bravo, NIH Deputy Director for Extramural Research, acknowledged, "Some people share their toys better than others." But the explanation for why so much NIH data are kept under wraps may be more serious than that. Data secrecy is becoming the norm rather than the exception, in an era when researchers--even those who have public funding--are increasingly likely to have commercial interests to protect.

According to a 2003 survey of 171 universities that received NIH grants by the then-General Accounting Office, 91 percent held equity options in the very companies for which they were developing technologies. Some academic institutions receive over $10 million in royalties per year for technologies they have developed. And individual researchers--including some who have refused to release their data in response--have also received funding from sponsoring drug companies. These commercial ties, and the secrecy they spawn, have real consequences for physicians who must rely on research results that may not be entirely disinterested.

It is difficult to know how many dangerous treatments might remain on the market, unchallenged, because of data secrecy. In the case of Prozac for teens, the data withheld by researchers could show that Prozac is not safe for children--an important development, given that it is currently the only anti-depressant approved by the FDA for the treatment of children. In the case of the study showing that the brains of children with ADHD are smaller, it means that stimulant drugs continue to be prescribed even though it is not clear whether brain shrinkage in children with ADHD is caused by the disease--or by the drugs used to treat the disease.

Wondering how widespread the problem of NIH secrecy was, I reviewed the data-sharing exemptions in Circular A-110 and all extramural grants awarded by the NIH in 2005. What I found was that, despite the lofty claims of data-sharing, there are so many exemptions in the guide and the Shelby amendment that they actually serve to codify data secrecy. For example, only researchers conducting studies that cost more than $500,000 in direct costs annually are required to file a data-sharing plan. Data are also exempt if they are not cited as part of a federal policy or regulation that has the "force and effect of law"--an exclusion that single-handedly eliminates virtually all NIH data. After reviewing all of the grants awarded by the NIH during 2005 and finding that virtually none of the data would fall under the conditions of mandatory release, I asked the NIH to identify any studies that had been released under the Shelby Amendment. Their answer was surprisingly frank: I was told that, "despite numerous requests" for data since the Shelby Amendment was passed in 1999, "none met the criteria of the regulation."

JEANNE LENZER is a freelance medical investigative journalist and a Knight Science Journalism Fellow at MIT.

"But once we spread out into space and establish independent colonies, our future should be safe," said Hawking, who was due to receive the world's oldest award for scientific achievement, the Copley medal, from Britain's Royal Society on Thursday.

Previous winners include Albert Einstein and Charles Darwin.

In order to survive, humanity would have to venture off to other hospitable planets orbiting another star, but conventional chemical fuel rockets that took man to the moon on the Apollo mission would take 50,000 years to travel there, he said.

Hawking, a 64-year-old father of three who rarely gives interviews and who wrote the best-selling "A Brief History of Time", suggested propulsion like that used by the fictional starship Enterprise "to boldly go where no man has gone before" could help solve the problem.

"Science fiction has developed the idea of warp drive, which takes you instantly to your destination," said.

"Unfortunately, this would violate the scientific law which says that nothing can travel faster than light."

However, by using "matter/antimatter annihilation", velocities just below the speed of light could be reached, making it possible to reach the next star in about six years.

"It wouldn't seem so long for those on board," he said.

The scientist revealed he also wanted to try out space travel himself, albeit by more conventional means.

"I am not afraid of death but I'm in no hurry to die. My next goal is to go into space," said Hawking.

And referring to the British entrepreneur and Virgin tycoon who has set up a travel agency to take private individuals on space flights from 2008, Hawking said: "Maybe Richard Branson will help me."

The Antikythera Mechanism, sometimes called the world's first computer, has now been examined with the latest in high-resolution imaging systems and three-dimensional X-ray tomography. A team of British, Greek and American researchers was able to decipher many inscriptions and reconstruct the gear functions, revealing, they said, "an unexpected degree of technical sophistication for the period."

The researchers, led by Tony Freeth and Mike G. Edmunds, both of the University of Cardiff, Wales, are reporting the results of their study in Thursday's issue of the journal Nature.

They said their findings showed that the inscriptions related to lunar-solar motions and the gears were a mechanical representation of the irregularities of the Moon's orbital course across the sky, as theorized by the astronomer Hipparchos. They established the date of the mechanism at 150-100 B.C.

The Roman ship carrying the artifacts sank off the island of Antikythera around 65 B.C. Some evidence suggests that the ship had sailed from Rhodes. The researchers speculated that Hipparchos, who lived on Rhodes, might have had a hand in designing the device.

In another article in the journal, a scholar not involved in the research, François Charette of the University of Munich museum, in Germany, said the new interpretation of the Antikythera Mechanism "is highly seductive and convincing in all of its details." It is not the last word, he concluded, "but it does provide a new standard, and a wealth of fresh data, for future research."

Historians of technology think the instrument is technically more complex than any known device for at least a millennium afterward.

The mechanism, presumably used in preparing calendars for seasons of planting and harvesting and fixing religious festivals, had at least 30, possibly 37, hand-cut bronze gear-wheels, the researchers reported. An ingenious pin-and-slot device connecting two gear-wheels induced variations in the representation of lunar motions according to the Hipparchos model of the Moon's elliptical orbit around Earth.

The functions of the mechanism were determined by the numbers of teeth in the gears. The 53-tooth count of certain gears, the researchers said, was "powerful confirmation of our proposed model of Hipparchos' lunar theory."

The detailed imaging revealed more than twice as many inscriptions as had been recognized from earlier examinations. Some of these appeared to relate to planetary as well as lunar motions. Perhaps, the researchers said, the mechanism also had gearings to predict the positions of known planets.

Dr. Charette noted that more than 1,000 years elapsed before instruments of such complexity are known to have re-emerged. A few artifacts and some Arabic texts suggest that simpler geared calendrical devices had existed, particularly in Baghdad around A.D. 900.

It seems clear, Dr. Charette said, that "much of the mind-boggling technological sophistication available in some parts of the Hellenistic and Greco-Roman world was simply not transmitted further," adding, "The gear-wheel, in this case, had to be reinvented."

The Department of Justice has declared today National Methamphetamine Awareness Day. What better way to observe it than taking a break from the hype? Rather than repeating the popular fiction about methamphetamine (that use is skyrocketing, that only stepped up policing will counter the trend, and that addiction is untreatable), let's take a moment today to consider the evidence.

First, methamphetamine use is not prevalent. Although some 12 million Americans have tried methamphetamine, this is far fewer than the number who have tried inhalants (23 million), hallucinogens (34 million), cocaine (34 million), or marijuana (96 million). Of those who have tried methamphetamine, only 1.5 million have used the drug in the last year; and only 583,000 have used it within the last 30 days.

There is no indication that methamphetamine use is increasing. The proportion of Americans who use methamphetamine on a monthly basis has hovered in the range of 0.2 percent-0.3 percent since 1999. In fact, according to the 2005 Monitoring the Future survey, the percentage of high school seniors who reported using methamphetamine in the last year fell to a low of 2.5 percent in 2005. (Use of depressants, meanwhile, increased from a low of 2.8 percent in 1992 to around 7 percent in 2005.)

Second, policing is not "taking care" of methamphetamine. While limits on purchases of precursors have pushed many illicit labs out of our neighborhoods, the drug is still being manufactured -- just now it's across the border. Indeed, methamphetamine is now as available and cheap as it has ever been. This comes as no surprise. As long as demand for an illegal drug exists, there will be supply to meet it.

While policing has failed to curtail use of methamphetamine, it has successfully overloaded our jails and prisons. In the 1980s-90s, California followed national trends by relying increasingly on punishment and prisons as its primary response to arrests for illicit drug use. The total number of people imprisoned in California for drug possession quadrupled between 1988 and 2000, peaking at 20,116.

It was in response to this trend that California voters decided to change tactics. In 2000, 61 percent of California voters passed Proposition 36, the treatment-instead-of-incarceration law, which provides treatment to over 35,000 Californians convicted of nonviolent low-level drug offenses each year. Over half (53 percent) of Prop. 36 participants -- over 19,000 people -- enter treatment for methamphetamine abuse each year.

Prop. 36 has provided valuable evidence that methamphetamine addiction is quite treatable. According to state data on Prop. 36, methamphetamine users have a treatment completion rate of 35 percent, higher than users of cocaine/crack (32 percent) or heroin (29 percent). Although this was an important learning opportunity for policymakers, it was not news to treatment specialists. In fact, there have been at least twenty recent studies showing the efficacy of methamphetamine treatment.

The next step for policymakers is to provide treatment on demand, so that people suffering from addiction have access to treatment outside of the criminal justice system. It is both cheaper and better for public safety to provide treatment to those who need it sooner rather than later.

Other evidence shows that California's public health measures have not gone far enough. Although the Governor signed the Pharmacy Syringe Sale and Disease Prevention Act in 2004, well under half of California's 58 counties have implemented the program to allow nonprescription purchases of up to ten syringes at pharmacies. This is literally killing some of our state's most vulnerable residents.

According to the California Society of Addiction Medicine, 30-50 percent of those with newly identified HIV-infection use methamphetamine. Increasing the availability of sterile syringes through syringe exchange programs, pharmacies, and other outlets is proven to reduce unsafe injection practices, curtail transmission of HIV/AIDS and hepatitis, increase safe disposal of used syringes, and help intravenous drug users obtain drug education and treatment.

The truth about methamphetamine is that its use is not growing exponentially, that addiction is treatable, and that the risks it poses to public health can be mitigated.

Margaret Dooley, who is based in San Diego, is the outreach coordinator for the Drug Policy Alliance.

"This document can be seen today as the first step toward a serious deepening of the military confrontation in space," the Interfax news agency quoted Vitaly Davydov, deputy head of the Russian space agency Roskosmos, as saying.

"Now the Americans are saying that they want not only to go to space but they want to dictate to others who else is allowed to go there," Davydov said, according to the report.

The order says the United States will "preserve its rights, capabilities, and freedom of action in space; dissuade or deter others from either impeding those rights or developing capabilities intended to do so" and "deny, if necessary, adversaries the use of space capabilities hostile to U.S. national interests."

Davydov criticized what he said were U.S. plans to deploy weapons in space and said that Russia could respond if the United States does so.

The White House has said the policy does not call for the development or deployment of weapons in space.

As the U.S. space policy was being reviewed last year, Russian Defense Minister Sergei Ivanov threatened retaliatory steps if any country put weapons in space.

Moscow's concerns about space-based weapons go back to the Soviet-era space race and U.S. President Ronald Reagan's 1980s plans for a "Star Wars" missile defense system.

Bush's order, signed more than two months ago, was not publicly announced.