Barack Obama's Address at the American Israel Public Affairs Committee COLUMBUS, Ohio - Iran represents one of the world's most grave foreign policy challenges, but don't look for much gravity in the speeches to American Israel Public Affairs Committee this week by the top three Republican presidential candidates. There will be plenty of empty fist-shaking and ridicule of President Obama at the pro-Israel lobbying group, but not a single new thought for preventing Iran from developing a nuclear weapon. The three candidates - Mitt Romney, Rick Santorum and Newt Gingrich - have consistently been at their most dangerous when discussing the Middle East, combining a simplistic bellicosity toward the Islamic world with a reflexive agreement with the Israeli right. They routinely misread the American Jewish community and the electorate at large as being monolithically in favor of military action against Iran. On Sunday, Mr. Romney said Iran will finish a nuclear weapon if Mr. Obama is re-elected, but not if Mr. Romney defeats him. How, precisely, will he disarm Iran? By imposing crippling sanctions, he said, and keeping a military strike on the table. That, of course, is exactly what the Obama administration has already done (and what the last Republican president did not do well enough). The sanctions now in place are the toughest ever, choking off Iran's exports. On Sunday, in his speech to Aipac, Mr. Obama made clear that he will not accept a nuclear-armed Iran, and is prepared to use military force to prevent it if necessary. But he said he prefers the route of diplomacy, and regrets the "loose talk of war." Does Mr. Romney have a problem with that? Would he actually disdain diplomacy in this kind of situation, reducing his State Department to an empty shell? Considering that he seems to regard anything short of a bombing threat as a sign of weakness, don't expect to hear an answer in his speech on Tuesday. The other candidates have either ignored reality or created their own. Mr. Gingrich, apparently too busy campaigning to read a newspaper, or simply not caring about the truth, blithely said on Sunday that there was no evidence the president is prepared to stop Iran. Mr. Santorum bizarrely suggested recently that the Obama administration is helping Iran develop a weapon by leaking Israel's plans for an attack. The leaks have actually come largely out of Israel and have been gleefully repeated by the American right. The administration would rather let Iran go nuclear than give up its oil, he charged. That's too ridiculous to even bother refuting, but it's hardly out of line with a Republican field that has responded to the globe's most serious issues with precarious posturing.