When President Bush visits Israel next week, he should offer to bring that ally fully into the U.S. missile defense network a step that might forestall an Israeli attack on Iran this year.

Two of the most strategically minded members of Congress I know, Reps. Mark Kirk, R-Ill., and Jane Harman, D-Calif., have enlisted 63 colleagues to urge the move as Bush prepares to commemorate the 60th anniversary of Israel's founding.

Specifically, the bipartisan group is calling on Bush to give Israel the advanced X-band radar system that would enable Israel to knock down Iranian missiles early in flight.

"It would be an appropriate birthday gift," Harman told me in an interview, "and would help ensure that Israel survives to celebrate its 120th."

Equally important in the short run, Kirk said, "it would lower everyone's temperature around Iran's nuclear and missile programs" and reduce the likelihood of an Israeli attack on Iran or a joint attack with the United States that would could have devastating worldwide repercussions.

Middle East experts I've talked to say the chances are 50-50 that Israel will try to destroy Iran's nuclear installations or ask that the United States join it in doing so.

The attack would come this year, these experts say, because Israel fears that a new U.S. president, especially a Democrat, would engage in drawn-out diplomacy with Iran, whose regime would use the time to continue developing nuclear weapons and the missiles to deliver them.

Separate from the nuclear issue, several Mideast experts I trust moderates, not super-hawks also think that the chances of a U.S.-Iran war are greater if Sen. Barack Obama, D-Ill., gets elected than Sens. Hillary Rodham Clinton, D-N.Y., or John McCain, R-Ariz., because Iran may judge him a "weak" president on the model of Jimmy Carter, "test" him more aggressively and miscalculate his resolve.

Possible Iranian "tests" include inspiring a Shiite militia takeover of the Iraqi government, attacks designed to humiliate the United States as its troops withdraw, an attempt by Iran-aided Hezbollah to topple the government of Lebanon or joint Hezbollah-Hamas attacks on Israel.

On the nuclear front, the logic for an Israeli attack on Iran is this: Israel regards Iran's nuclear and missile programs as a threat to its existence, especially because Iranian President Mahmoud Ahmadinejad has explicitly declared intent to "annihilate" the "Zionist regime."

In 1981, Israeli planes bombed Iraq's Osirak nuclear reactor, and last September Israel did the same to a Syrian reactor built with help from North Korea, which would seem to set the precedent for an attack on Iran.

Neither of those nuclear programs was as extensive as Iran's is today and Iran already has tested missiles capable of reaching Israel.

However, an attack on Iran's facilities would be difficult because they are numerous, scattered and buried which is why Israel might ask for a joint attack with U.S. warplanes and cruise missiles.

Bush is being urged by some neoconservative activists to destroy Iran's nuclear threat before he leaves office. Some antineocons claim that there is a struggle going on within the administration over the issue between the State and Defense departments, which favor diplomatic and economic pressure on Iran and oppose military action, and Vice President Dick Cheney, who believes diplomacy will never work as, indeed, it so far has not.

Whether the United States actually joined in an Israeli attack, the United States would not avoid blame and the consequences could be dire perhaps including Iranian-inspired terrorist attacks here, all-out Shiite militia assaults on U.S. troops in Iraq and disruption of worldwide oil supplies.

As an alternative to a military strike, commentators headed by syndicated columnist Charles Krauthammer and Clinton advocate that the United States should counter Iran's nuclear threat with Cold War-style deterrence.

Clinton said last month that the United States could "totally obliterate" Iran if it attacked Israel with nuclear weapons. She also proposed extending America's nuclear "umbrella" to Arab states in the region to keep them from "going nuclear."

Kirk, while not opposing deterrence, said that including Israel fully in the U.S. missile-defense system would be a better alternative, particularly because "deterrence only works against a rational regime" that would not risk destruction of its own population. Iran's leaders, on the other hand, adore martyrdom.

Kirk and Harman are long-standing advocates of missile defense for Israel. In the 1990s, Harman, formerly ranking member on the Intelligence Committee, promoted development of the Arrow antimissile system, which is now Israel's primary defense against Iran.

More recently, Kirk, a Naval Reserve intelligence officer and co-chairman of the bipartisan House Iran Working Group, successfully urged the Bush administration to include Israel in the U.S. global antimissile network.

X-band radar, Kirk said, would "allow Israel and the United States to see the Earth through a common window" and more than quintuple Israel's warning time against an Iranian missile attack from one minute with its current system to six minutes, and allow an intercept with Arrow missiles outside Israeli territory.

Kirk and Harman persuaded a broad swath of influential House Members to join in a letter to Bush urging the project, including the chairmen and ranking members of the Armed Services and Foreign Affairs committees and arch-conservatives and left-liberals.

Additionally, Kirk said, he's been "working it hard" with Secretary of State Condoleezza Rice, Defense Secretary Robert Gates, White House National Security Adviser Steven Hadley and other U.S. and Israeli officials in advance of Bush's visit.

He told me he's concerned that officials in both countries have other, more short-term priorities diplomatic moves for the Mideast peace process and research on short-range antirocket systems but that these could be part of a package Bush delivers in Israel along with the X-band system.

To prevent a war, Bush should take Kirk and Harman's advice. And, I'd say, if a Democrat becomes president, Harman would make a great director of national intelligence. And, if McCain is elected, Kirk ought to be his national security adviser.

(Morton Kondracke is executive editor of Roll Call, the newspaper of Capitol Hill.)