Some dressed in costume, including a hooded prisoner in an orange jumpsuit, a devilish rendition of President Bush and two grim reapers. One man wore a red cheerleader outfit with "Radical" emblazoned on the jersey.

The demonstrators held up yellow police tape along a three-block stretch in front of the White House.

Thousands of protesters clogged New York City's streets as they marched from the United Nations headquarters. Some people lay down in the middle of the street, while others carried signs saying "Expose 9/11" and "This war should be over." They also handed out fliers reading, "Drive out the Bush regime."

Lydia Sugarman, 82, of Manhattan, said she believed in the power of demonstrating.

"That's how we got our civil rights," she said. "If we didn't protest we wouldn't be Americans."

White House spokeswoman Nicole Guillemard defended the administration's Iraq policy.

"Our constitution guarantees the right to peacefully express one's views. The men and women in our military are fighting to bring the people of Iraq these same rights and freedoms," she said. "The president believes it is important to stay on the offense in Iraq."

World Can't Wait was founded in 2005 and has organized several marches since then, including a nationwide protest coinciding with Bush's State of the Union address in January, according to the group's Web site. Supporters listed on the site include Edward Asner, Ed Begley Jr. and Jane Fonda and activists such as the Rev. Jesse Jackson, the Rev. Al Sharpton and Cindy Sheehan.

In Seattle, a person carrying a rifle wrapped in a blanket was among five people arrested. The charges against the other people ranged from resisting arrest to assault.

"They're still investigating to determine what that person was doing with the rifle," said Seattle Police spokeswoman Debra Brown.

The march through Seattle's streets was peaceful as protesters chanted, waved signs and wore costumes mocking administration officials. One woman dressed as a pageant queen with a sash that read, "I Miss America."

In Portland, Ore., at least 10 people were detained because they did not follow police instruction to get out of the street during a protest march through downtown.

Cathe Kent, a police spokeswoman, said one person, 26-year-old Christopher Knudtsen, also faced a charge of attempted assault for trying to attack a police officer.

An estimated 800 people, mostly college age, chanted "Impeach Bush" and carried signs, including one that read: "We Can't Wait for 2008."

Hundreds marched in Los Angeles, carrying caskets draped in U.S. flags to a federal courthouse, where protesters held a mock marriage of church and state.

In Asheville, N.C., dozens of University of North Carolina students walked out of classes. In Chicago, thousands of people flooded Michigan Avenue waving anti-Bush signs.

"We are at a defining moment for this country and our people," said World Can't Wait's Rick Strandlof in Reno, Nev.

"I was seventeen years old and just returned to [my home state] when Foley began to e-mail me, asking if I had ever seen my page roommates naked and how big their penises were," said the page in the 2002 class.

The former page also said Foley told him that if he happened to be in Washington, D.C., he could stay at Foley's home if he "would engage in oral sex" with Foley.

The page told ABC News he was interviewed this week by FBI agents who had a six-page list of questions about Foley and the exchanges.

The second page who talked with ABC News, a graduate of the 2000 page class, says Foley actually visited the old page dorm and offered rides to events in his BMW.

"His e-mails developed into sexually explicit conversations, and he asked me for photographs of my erect penis," the former page said.

The page said Foley maintained e-mail contact with him even after he started college and arranged a sexual liaison after the page had turned 18.

The third page interviewed by ABC News, a graduate of the 1998 page class, said Foley's instant messages began while he was a senior in high school.

"Foley would say he was sitting in his boxers and ask what I was wearing," the page said.

"It became more weird, and I stopped responding," the page said.

All three pages described similar instant message and e-mail patterns, with remarkably similar escalations of provocative questions.

"He didn't want to talk about politics," the page said. "He wanted to talk about sex or my penis," the page said.

The three new verbal accounts are in addition to two sets of sexually explicit instant messages provided to ABC News by former pages.

An online story on the Drudge Report Thursday claimed one set of the sexually explicit instant messages obtained by ABC News was part of a "prank" on the part of the former page, who reportedly says he goaded the congressman into writing the messages.

"This was no prank," said one of the three former pages who talked to ABC News today about his experience with the congressman.

Democrats and some Republicans have accused Hastert and his leadership team of brushing off early indications of a problem -- including what they called an "over-friendly" e-mail that Foley sent to a Louisiana boy in 2005 -- that might have led investigators to find the explicit instant-message exchanges that had occurred in previous years. Two high-ranking House Republicans have said they told Hastert about that e-mail, and another lawmaker says he told Hastert's staff.

Kirk Fordham, Foley's former chief of staff, said this week that he repeatedly alerted Hastert's staff in 2003 to complaints that the Florida lawmaker was showing inappropriate interest in male pages, who are high-schoolers spending a semester or two working for Congress. The FBI spent more than three hours yesterday interviewing Fordham.

Some Republicans said they are most concerned about Fordham's assertions. Scott Palmer, the speaker's top aide, has denied the allegations and spent much of Wednesday night rummaging through old e-mails and files to determine whether he ever corresponded with Fordham, a source close to Hastert said. Palmer, who was described as very emotional, told Hastert that Fordham's assertions are false, the source said.

Hastert's office has been on edge. Deputy Chief of Staff Mike Stokke, who handles politics for the speaker, has offered to resign, two sources close to Hastert said, and several aides have expressed frustration that Ted Van Der Meid, the top counsel in the office, did not do a better job monitoring the Foley situation. Hastert did not accept Stokke's resignation offer, the source said.

Hastert, addressing reporters in Batavia, Ill., reasserted that he knew nothing of complaints about Foley's behavior until the day the Floridian resigned last week. The speaker rejected calls for his resignation by a handful of conservative groups, saying: "I haven't done anything wrong, obviously. And we need to come back." At the same time, he said, "We're taking responsibility, because ultimately, as someone has said in Washington before, the buck stops here."

Hastert suggested that Democrats may have known about the lewd instant messages and leaked them for partisan advantage, but he said he had no evidence.

Hastert had hoped to announce the bipartisan appointment of former FBI director Louis J. Freeh to look into ways to improve the page program, in which teenagers live in a Capitol Hill dorm and attend a special school. But when he called Minority Leader Nancy Pelosi (D-Calif.) early in the afternoon, she declined to go along with the plan.

Pelosi saw the Freeh proposal as a ploy to burnish the GOP's image, aides said. She told the speaker that investigators should examine whether existing rules and procedures were followed before the House considers new rules, the aides said.

Rather than presenting Freeh as an appointee backed only by Republicans, Hastert delayed his remarks and dropped the idea.

At the ethics committee's news conference, Hastings said he thinks Hastert "has done an excellent job" as speaker but added that as committee chairman he would be able to render impartial judgments on the Foley affair.

The committee has a stormy history, in part because Hastert replaced key members in early 2005 as the panel was investigating then-Majority Leader Tom DeLay (R-Tex.). The committee was essentially paralyzed, but public furor over the Foley scandal forced it into action on a high-profile issue.

The four-person subcommittee handling the Foley matter consists of Hastings, Berman, Judy Biggert (R-Ill.) and Stephanie Tubbs Jones (D-Ohio). Berman said that "we are dealing with a fundamental institutional issue" concerning the handling of information and warnings about Foley.

As he had done before, Hastert described the Foley chronology yesterday in ways that some Republican colleagues challenge. "Could the Page Board have handled it better?" he said. "In retrospect, probably, yes."

But only two of the Page Board's six members -- three lawmakers and three staffers -- knew anything about the e-mail to the Louisiana boy. Among those kept in the dark were Reps. Shelley Moore Capito (R-W.Va.) and Dale E. Kildee (D-Mich.). They have said they should have been brought into the decision-making process earlier this year.

Hastert was feistier in a Chicago Tribune interview published yesterday. "The people who want to see this thing blow up," he said, "are ABC News and a lot of Democratic operatives, people funded by George Soros," a major contributor to liberal causes. "I saw Bill Clinton's adviser Richard Morris was saying these guys knew about this all along."

Morris is a former Clinton consultant who was been sharply at odds with the former president for years. Hastert offered no proof for his assertions, and Democrats called them absurd and laughable.

High-ranking House Republicans, after challenging Hastert's handling of the Foley matter in recent days, issued statements of support yesterday.

President Bush called Hastert last night to offer his support. "He's saying at this point that the speaker should not resign," spokesman Tony Snow said.

Meanwhile yesterday, a 26-year-old Atlanta man says Foley began sending him sexually suggestive messages and invited him to his Washington home after he served as a congressional page nine years ago. Tyson Vivyan said Foley began sending him online instant messages a month or two after his nine-month stint as a page ended in June 1997. Foley entered Congress in January 1995.

Vivyan's account appears to show the earliest exchange of suggestive messages reported so far between Foley and former pages. Vivyan said he played along at first, thinking it was someone he knew. After weeks of peppering the anonymous message sender with questions, he said he figured out who it was and refused to engage in the sexual banter that Foley tried to instigate.

"I had absolutely no sexual interest in him. He was a man twice my age," said Vivyan, who added: "I don't call my self gay, I don't call myself straight."

Vivyan, who is divorced, said he found the congressman's behavior "morally reprehensible" but tried to maintain a platonic professional relationship in which they talked about legislation and "votes on the Hill."

He said that in 1999 Foley invited him and another former page over to his home for pizza. Vivyan said they went and "everything was completely platonic and nonsexual."

Also yesterday, ABC News reported that three more former congressional pages have come forward to reveal what they call "sexual approaches" over the Internet from Foley. The pages served in the classes of 1998, 2000 and 2002, ABC said, and they do not want their names used.

"They would have a great time with it, which would be a big distraction," said Charles Black, a longtime GOP strategist with close ties to the White House.

"The control of the House was in play before the Foley thing happened, but this does not help," Black said. "If Democrats were to take the House, that would make it harder to get Bush initiatives through."

The House, with Hastert at the helm, has generally delivered for Bush, even when the Senate has not.

Democrats are believed to have a better shot at winning control of the House than of the Senate, although recent developments have raised Democratic expectations for both chambers.

Despite public expressions of support for Hastert by Bush and Vice President
Dick Cheney, the White House worked to distance itself from the firestorm. "We're not getting into telling the House how to do its business," White House spokesman Tony Snow said Thursday.

Even if Republicans do retain control, it probably would be by reduced margins, increasing the likelihood of gridlock. And even if Hastert doesn't step down - Democrats and some Republicans advocate that he resign as speaker - there now is a huge cloud over his leadership.

Hastert on Thursday said he was "deeply sorry this has happened" and took responsibility as the top House leader, but he held fast against calls for him to quit.

White House aides suggest they are doing little to actively prop up Hastert, despite expressions of support from Bush, Cheney and Snow.

Bush said Foley's behavior "disgusted" him - but that he supported Hastert. Cheney said "it makes no sense" for Hastert to step down, predicting that Republicans would retain both chambers of Congress.

Still, in an interview with the Washington Examiner newspaper, Cheney said that if Democrats did seize control, "I don't think we fear investigations."

"I don't think they would get much done, if that's all they've got. And I don't think there's great enthusiasm on the part of the country for that," Cheney added.

Republican strategists worried that the scandal could suppress Election Day turnout among the social conservatives that form the GOP base.

"We understand people's real concern about this. I mean, people ought to be concerned. It's a hideous thing," said Snow.

The scandal comes amid growing public opposition to the Iraq war and lagging confidence in GOP leadership.

In an AP-Ipsos poll conducted this week after the Foley revelations surfaced, about half of likely voters said recent disclosures of corruption and scandal in Congress will be very - or extremely - important in their vote next month. Democrats enjoyed a nearly 2-to-1 advantage as the party better able to fight corruption.

Republicans worried the scandal would ripple throughout the electorate, turning voters against GOP incumbents who had nothing to do with it - especially if evidence develops to back up allegations that some Republican leaders knew about Foley's activities months or years ago but failed to act.

Republicans pushed for quick action in the congressional and
FBI investigations.

At the same time, some gallows humor circulated.

"It took Bob Woodward's book off the front pages," said GOP consultant Rich Galen, referring to the new book by the Washington Post journalist that portrays Bush as intransigent in his defense of the Iraq war and his advisers as bitterly divided.

The page scandal "obviously keeps Republicans from talking about what they want to talk about," said Galen. But he warned against leaping to conclusions that it would automatically translate into Republican losses.

He noted that, in 1998, the situation was reversed and he and other Republicans "were rubbing our hands together in glee every day we had the Democrats talking about Monica (Lewinsky) and Bill (Clinton). And guess what happened?" Republicans suffered midterm election losses.

"We always flirt with danger when trying to predict future events based upon current data," Galen said. "When something flashes this hot, it often can't sustain itself and burns out quickly."

In some videos, the troops do not appear to have been seriously injured; in one, titled "Sniper Hit" and posted on YouTube by a user named 69souljah, a serviceman is knocked down by a shot but then gets up to seek cover. Other videos, however, show soldiers bleeding on the ground, vehicles exploding and troops being loaded onto medical evacuation helicopters.

At a time when the Bush administration has restricted photographs of the coffins of military personnel returning to the United States and the Pentagon keeps close tabs on videotapes of combat operations taken by the news media, the videos give average Americans a level of access to combat scenes rarely available before, if ever.

Their availability has also produced some backlash. In recent weeks, YouTube has removed dozens of the videos from its archives and suspended the accounts of some users who have posted them, a reaction, it said, to complaints from other users.

More than four dozen videos of combat in Iraq viewed by The New York Times have been removed in recent days, many after The Times began inquiries.

But many others remain, some labeled in Arabic, making them difficult for American users to search for. In addition, new videos, often with the same material that had been deleted elsewhere, are added daily.

Russell K. Terry, a Vietnam veteran who founded the Iraq War Veterans Organization, said he had mixed feelings about the videos.

"It's unfortunate there's no way to stop it," Mr. Terry said, even though "this is what these guys are over there fighting for: freedom of speech."

One YouTube user, who would not identify himself other than by his account name, facez0fdeath, and his location, in Britain, said by e-mail that he posted a video of a sniper attack "because I felt it was information the U.K. news was unwilling to tell."

"I was physically sickened upon seeing it," he said, adding, "I am wholly opposed to any form of censorship."

The video he posted, which had been viewed more than 33,000 times, was removed earlier this week.

Another YouTube user, who said he was a 19-year-old in Istanbul and who posted more than 40 videos of Iraq violence, said via e-mail that "anti-war feelings and Muslim beliefs (the religion of peace) motivates me."

Neal O. Newbill, a freshman at the University of Memphis who viewed some of the YouTube videos and posted comments on them, said in an interview that he was enraged by the recorded chants of "Allahu Akbar," Arabic for "God is great," that follow some of the sniper attacks.

But Mr. Newbill added that he was awed by the size of the blasts from the improvised explosive devices, or I.E.D.'s, used against American vehicles. A son, nephew and grandson of American veterans, Mr. Newbill said he had sought out the videos, searching on YouTube for "I.E.D.," "because I like watching stuff blow up."

The Web sites also contain a growing number of video clips taken by American soldiers. One shows the view from the back of a truck containing several members of a platoon, whose vehicle then hits an I.E.D. and is turned on its side. A few videos also show American servicemen or private security guards firing at attackers, and one shows an American rocket-propelled grenade hitting a building from which insurgents are firing.

A spokesman for United States Central Command, which oversees troops in Iraq, said the military was aware of the use of common Internet sites by both insurgent groups and American military personnel.

"Centcom is aware we are facing an adaptive enemy that uses the Internet as a force multiplier and as a means of connectivity," Maj. Matt McLaughlin, the spokesman, said by e-mail.

While posting of Web logs, pictures and videos by American troops is subject to military regulations, Major McLauglin said, "Al Qaeda uses the Internet and media to foster the perception that they are more capable than they are."

Some of the videos are obvious propaganda, with Arabic subtitles and accompanying music, while others simply have scenes without sound or graphics. They appear to be real, though the results of attacks are not always clear.

One frequently posted video shows individual photographs of several hundred American soldiers allegedly killed by a Baghdad sniper referred to as Juba. But a television news report from the German weekly Der Spiegel that also has been posted on the video sites shows an interview with one American soldier whom the insurgent group claimed to have killed but whose protective vest stopped the sniper's bullet.

Geoffrey D. W. Wawro, director of the Center for the Study of Military History at the University of North Texas and a former instructor at the United States Naval War College, said the erosion of the command structure of terrorist and insurgent groups had led them to increase their reliance on the Internet and videos to gain recruits.

American troops, too, have always sent snapshots home from the front, Mr. Wawro said, and digital pictures and video are simply a new incarnation of that.

"This is how the new generation does things," he said.

"It results in a continued trivialization of combat and its effects," Mr. Wawro added, "but no one feels completely comfortable saying, Don't do it."

YouTube does feel comfortable saying so, however, as does Google Video. Both have user guidelines that prohibit the posting of videos with graphic violence, a measure that spokeswomen for each service said was violated by many of the Iraq videos.

Julie Supan, senior director of marketing for YouTube, said the company removed videos after they were flagged by users as having inappropriate content and were reviewed by the video service.

In an e-mail message, Ms. Supan said that among the videos removed were those that "display graphic depictions of violence in addition to any war footage (U.S. or other) displayed with intent to shock or disgust, or graphic war footage with implied death (of U.S. troops or otherwise)."

The deaths in Baghdad are directly bound up with the influx into the Iraqi capital of US troops as part of an offensive launched by the Pentagon to suppress sectarian militias and forestall the breakup of the puppet regime of Iraqi Prime Minister Maliki.

This is a brutal action, with American troops going door-to-door in targeted neighborhoods, breaking down doors and arresting alleged militia members. Very little has been reported about the offensive, and no figures have been released of Iraqi dead and wounded, or the number arrested. However, ABC News noted Thursday night that US forces have raided 100,000 buildings over the past two months.

Eight of the 13 deaths in Baghdad were attributed to small arms fire rather than improvised explosive devices, the leading killer of American soldiers in Iraq. A US Army spokesman, Lt. Col. Barry Johnson, told the press, "When you're conducting operations and you've doubled the number of troops doing operations in Baghdad, there is more opportunity-as there is much more activity as they go into more neighborhoods-for attacks to occur and casualties to result." He said insurgents "are reacting to an opportunity to attack."

According to a report Wednesday in the Los Angeles Times, "US military deaths appear to be rising, even as fatalities among Iraqi security forces have fallen... As American fatalities increased, the number of deaths among Iraqi security forces fell in September to 150, the lowest number since June and among the lowest tallies in 18 months, according to the Brookings Institution Iraq Index."

These figures demonstrate the failure of the Bush administration's policy of shifting front-line military responsibilities to the troops and police of the US-installed regime in Baghdad headed by Maliki. With Iraqi troops either unable or unwilling to conduct the type of brutal counterinsurgency sweeps demanded in densely populated Baghdad neighborhoods, more than 15,000 American troops have been mobilized to carry out the dirty work-and take the ensuing casualties.

In addition to the small arms fire encountered in the house-to-house searches, the number of bombs planted is "at an all-time high," according to another military spokesman, Maj. Gen. William B. Caldwell. "This has been a hard week for US forces," he admitted.

Army Maj. Gen. James D. Thurman, commander of the Multinational Division Baghdad, told the Times last month that attacks against US-led coalition forces in Baghdad had reached an average of 42 a day-with about six causing casualties or equipment damage-up from 36 or 38 attacks. "Why are we seeing an increase in attacks?" he said. "Well, we have twice as many forces operating throughout the city now. We're challenging the anti-Iraqi forces where they live and operate."

In the bizarre terminology of the Pentagon, Iraqi insurgents-people who, as General Thurman admits, "live and operate" in Baghdad and fight against the Americans who have come 10,000 miles to occupy the country-are described as "anti-Iraqi forces."

Meanwhile, the Shiite leader Moqtada al-Sadr, whose political movement dominates the eastern half of Baghdad, issued a warning that he and his Mahdi Army militia were the likely next target for a massive US military onslaught. A top aide to al-Sadr, Sahib al-Amery, said Wednesday that a US attack on Sadr City, the main Shiite area on east side of Baghdad, was imminent.

"They want to turn it into mass graves similar to the previous ones conducted by the former regime," al-Amery said. "The occupation forces want to start a sectarian crisis on the pretext that there are Shiite militias."

US officials have issued a steady drumbeat of statements criticizing the Maliki government for not moving against al-Sadr's organization and against another big Shiite militia, the Badr Brigade, controlled by the Supreme Council for the Islamic Revolution in Iraq, one of the two main components of the ruling Shiite bloc that controls a majority of seats in parliament.

Secretary of State Condoleezza Rice flew to Baghdad Wednesday for talks with Maliki. Her trip, not announced in advance, was a manifestation of the deepening crisis of the US occupation regime. Rice's landing at the Baghdad International Airport had to be delayed by 30 minutes because of mortar fire near the facility.

Her trip was largely aimed at stepping up the pressure on Maliki and his government to support and participate in an attack on al-Sadr's forces.

She arrived in the Iraqi capital barely 24 hours after the Iraqi Interior Ministry suspended an entire Iraqi police brigade after charges that it had permitted or directly participated in sectarian death-squad killings. Members of the brigade were alleged to have taken part in a raid on a meatpacking plant in which 24 workers were seized and presumably executed. The bodies of seven of the kidnapped workers were found the next day.

According to the Iraq Coalition Casualty Count, which monitors deaths reported by the US military, 74 soldiers and Marines were killed in Iraq in September, the highest number since April, when 76 died. The death toll diminished during the summer, at least in part because of a deliberate decision by the Pentagon to scale back the number of American patrols, which, according to the New York Times, are down from a daily average of 400 in 2005 to only 100 a day this year.

It is quite likely that this decision was taken for political, not military reasons-to prevent the US death toll from hitting the 3,000 mark during the critical last two months of the 2006 election campaign. Total US deaths in Iraq are nearing 2,750. If American soldiers had died at September's rate throughout the summer, the death toll would have hit 3,000 only days before the November 7 vote.

A preliminary analysis of the September deaths, prepared by the Washington Post's web site, found that the 70 soldiers for whom biographical information was available came from 31 states and two US territories (Puerto Rico and Micronesia). There were 67 men and three women.

In terms of states, the largest number of deaths, six, was among Ohio soldiers, followed by five each from California and Texas, four from Florida, and three apiece from Georgia, Maryland, Missouri, Oklahoma, Pennsylvania and Washington.

The tragic waste of lives-a tragedy multiplied a hundredfold in terms of Iraqi war dead-is underscored when one considers the age at which these soldiers were killed. One was only 18 years old, five were 19, 9 were 20 years old, and 13 were 21 years old (the most common age). Three were in their 50s, the oldest of whom was 57.

The ongoing slaughter testifies to the bipartisan support for the continuation of the war. No prominent Democrat has criticized the intensification of US violence in Baghdad. On the contrary, many of the Democratic critics of the Bush administration have combined complaints about the government's incompetence and its strategic blunders with calls for more troops and more decisive military action to crush the Iraqi resistance.

"The Canadian men and women who serve there have gone willingly, knowing that not all of them will return," he said.

"When I went to Afghanistan and visited our troops there, I saw - as anyone could see first-hand there on the ground - just how dedicated, professional, skilled and courageous they are."

Thirty-nine Canadian soldiers have been killed in Afghanistan since Canada first sent troops there in early 2002.

"We see just how proud Canadians are of their soldiers and their families and we have also seen how difficult it is to bear the sorrows of their losses. But, ladies and gentlemen, that is the price of leadership in the world," Harper told the audience.

"It is also the price of moving the world forward."

Harper was in Calgary to receive the Woodrow Wilson Award for public service. He said Canadians want their country to be confident and to take a clear role in the world, even if it is not always the safest path.

They want "a Canada that doesn't just criticize, but one that can contribute," he said. "They want a Canada that reflects their values and interests, and that punches above its weight."

Soldiers' remains to arrive Friday evening

Harper, whose government was criticized by a Senate committee on Thursday for not doing a good job of explaining Canada's mission in Afghanistan, made his comments as the bodies of two Canadian soldiers were on their way back home to Canada.

Sgt. Craig Paul Gillam and Cpl. Robert Thomas James Mitchell were killed on Tuesday. They were both members of the Royal Canadian Dragoons, based in Petawawa, Ont. Their bodies were expected to arrive at 7 p.m. ET at CFB Trenton in eastern Ontario.

Gillam and Mitchell were providing security for a road construction project about 20 kilometres west of Kandahar when a handful of insurgents armed with rocket-propelled grenades and assault rifles attacked. Gillam and Mitchell were killed in the attack, which also left five other soldiers wounded.

They were the 38th and 39th Canadian soldiers to die in Afghanistan since 2002, when Canada first contributed troops to help stabilize the country for reconstruction.

Canada has more than 2,000 soldiers in Afghanistan, the majority stationed in the southern province of Kandahar.

"It's a pretty substantial, warm anomaly, comparable and even warmer than an anomaly found in the early '90s," Dr. Igor Polyakov, of the International Arctic Research Center in Fairbanks, Alaska, told CBC News.

The warming could change the thickness of Arctic sea ice as well as the amount of area it covers, affecting the marine ecosystem and the species that live there, he said.

"In 2004 we found this anomaly in the eastern Eurasian basin and now we are tracing this anomaly propagating further towards the Canadian part of the basin and towards Alaska," he said.

Prof. Julie Brigham-Grette, who is with the U.S. National Research Council, said changes have already been noticed off the coast of Alaska.

"A lot of the fishing vessels are following the northward shift in the ecosystem," she said. "A lot of the commercial fish are migrating northward as the warmer waters migrate northward."

The American researchers are working with international partners including Norway, Greenland and Canada.