The Bush administration appears set to offer Israel a powerful radar system that could greatly boost Israeli defenses against enemy ballistic missiles while tying them directly into a growing U.S. missile shield.

President George W. Bush is expected to discuss the matter during a visit to Israel starting on Wednesday to mark the 60th anniversary of the Jewish state amid mounting U.S. concern over perceived threats from Iran, people familiar with the matter said.

This is "probably the No. 2 issue" on Bush's agenda for the visit, second only to the Middle East peace process, said Rep. Mark Kirk, an Illinois Republican who has spearheaded calls in Congress for tighter U.S. missile-defense ties with Israel.

Gordon Johndroe, a White House spokesman, said in an e-mail, "While the U.S. and Israel cooperate closely on defense matters, there will not be any announcements during next week's visit." Bush is also to visit Saudi Arabia and Egypt.

Richard Lehner, a spokesman for the Pentagon's Missile Defense Agency, which is developing the multibillion-dollar layered shield, said questions about a new radar system for Israel were a "policy issue" outside the agency's purview.

Riki Ellison, a prominent missile-defense advocate with close ties to the Pentagon and companies involved in building the hardware, said he understood giving Israel the missile-tracking system was "on the table right now."

The system Bush may offer is known as a forward-based X-band radar. Transportable by air, it uses high-powered pulsed beams for extremely high-resolution tracking of objects in space such as a missile that could be tipped with a chemical, germ or nuclear warhead.

Built by Raytheon Co (RTN.N: Quote, Profile, Research), the system has been described by U.S. officials as capable of tracking an object the size of a baseball from about 2,900 miles (4,700 km) away.

It would let Israel's Arrow missile defenses engage a Shahab-3 ballistic missile about halfway through what would be its 11-minute flight to Israel from Iran, or six times sooner than Israel's "Green Pine" radar is currently capable of doing, Kirk said in a telephone interview on Friday.

'Parting Gift' from Bush?

Kirk is a commander in the U.S. Naval Reserves who confers with Israeli officials on missile defense. He serves one weekend a month as deputy director of intelligence in the Pentagon's National Military Command Center.

With an X-Band system at work, he said, a missile intercept theoretically would take place over Iran or a neighboring state and not over Israel.

"This is the best thing to lower tensions between Israel and Iran" because Iran presumably would be less likely to attack under such circumstances, Kirk said.

Nearly 70 members of Congress, including the top Democrat and Republican on the House of Representatives Armed Services Committee, sent a letter to Bush this week urging him to offer a warning radar that is "fully integrated" with the emerging U.S. shield.

The letter, dated May 5 and co-authored by Kirk and California Democratic Rep. Jane Harman, cited a call by Iranian President Mahmoud Ahmadinejad for Israel to be "wiped off the map" and said Iran's ballistic missile program was expanding.

An X-band radar would improve "battle management," adding to "early warning" from Israel's access since 2001 to the Defense Support Program military satellite network, hub of a U.S. system to detect missile launches worldwide, the letter said.

An Israeli defense official said Israel had discussed a range of "parting gifts" from Bush, who leaves office on Jan. 20, including military pacts and technologies.

Lehner, the spokesman for the U.S. Missile Defense Agency, said the Pentagon was planning to have four transportable X-band radars, including one already set up near Shariki in northern Japan to guard against missiles that could be fired by North Korea.

A second is due to be deployed at an unspecified location near Iran, possibly in eastern Turkey or Georgia, assuming permission is granted. In addition, the United States is awaiting final approval for a large, fixed-site, tracking radar in the Czech Republic scheduled for deployment by 2013.

The transportable X-band radar sites could "go wherever they are needed" at the request of U.S. combatant commanders, Lehner said.