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.