By Andrew C. Schneider, Associate Editor April 29, 2009 Barack Obama's White House meeting with Benjamin Netanyahu on May 18 is likely to be the tensest first encounter of a U.S. president and an Israeli prime minister in decades. The Israeli-Palestinian peace process, or lack of it, will be a major reason, with Obama needing progress to improve U.S. relations with the Muslim world. But what will really cause sparks to fly is their dispute over what to do about Iran's pursuit of nuclear weapons.Obama's willingness to engage Iran in direct diplomacy was a concern for Israeli leaders, and for American Jewish voters, even during last year's presidential campaign. Reassuring both groups about how strongly he was committed to Israel's security was a primary reason for his campaign swing through Israel last July, when he had his first meeting with then-opposition leader Netanyahu. For Netanyahu, though, warm words are nowhere near enough to lift concerns about Iran, particularly when Iranian President Mahmoud Ahmadinejad is openly calling for Israel's destruction. Simply put, Netanyahu wants Obama to get tough: Either get Iran to abandon its nuclear program or be prepared to use force. Because if you don't, he'll imply, we will. Indeed, Netanyahu telegraphed the message in an interview with The Atlantic shortly before he took office. An Israeli preemptive strike on Iran's nuclear problems would cause incalculable problems for the U.S., and it's far from clear that it would do Israel much good in the long run. It's certainly plausible that the Israeli Air Force could mount a bombing mission to hit a target anywhere in Iran. The immense distance would require mid-air refueling. That by itself is not a problem, but to strike Iran, Israeli jets would have to overfly Iraq. That would put the U.S. in a very uncomfortable position. Advertisement If the U.S. tried to force the Israeli jets down, the result could be an exchange of fire that would damage U.S.-Israeli relations for years to come. But if the U.S. allowed the Israeli jets to pass, it would effectively be condoning the mission. Tehran would blame the U.S. for the attack as much as Israel, and it would retaliate. It would ramp up attacks on U.S. forces in Iraq by means of Shiite militia proxies. Its naval forces would attempt to shut off oil shipping through the Persian Gulf, leading to combat with the U.S. Fifth Fleet. Oil prices would undoubtedly skyrocket. And it could lead to terrorist attacks against U.S. targets and retaliation against Israel by Hezbollah, Iran's Lebanese client. And there's another problem. The air strike might not work all that well. Iran, taking a cue from Israel's 1981 bombing of Iraq's Osirak nuclear reactor, has scattered its nuclear facilities around the country, burying them and otherwise protecting them. There's a strong probability that some of these facilities would survive an Israeli strike. At best, the Iranians would be set back, but they'd now be more determined than ever to get nuclear weapons, seeing them as a necessary deterrent to future strikes. Obama's problem is in convincing Netanyahu that it's in Israel's interest not to attack, to give diplomacy a chance to do its job. Netanyahu is willing to give Obama some time, but he won't wait all that long. From his perspective, Iran already crossed Israel's red line more than two months ago, when the International Atomic Energy Agency announced that Iran had far more enriched uranium than was previously believed. Israel has already shown it is willing to strike preemptively to keep a hostile neighbor from developing nuclear weapons, even at the risk of a breach with the U.S. In addition to the Osirak bombing in 1981, it also took out a Syrian facility in September 2007. If Netanyahu decides Iran is close to getting the bomb, he won't ask permission from Washington. He'll act.