Iranian President Mahmoud Ahmadinejad was pointedly left off the guest list for last week's Washington summit on nuclear security, which was attended by 47 world leaders. That's because President Barack Obama hoped to use the occasion to build support for a new round of international sanctions against Iran's nuclear development program. But Ahmadinejad is never one to stay home waiting forlornly for the phone to ring. Instead, he staged his own nuclear disarmament "summit" in Tehran this past weekend.Under the banner "Nuclear Energy for All, Nuclear Weapons for No One," the Iranian event had a less impressive guest list than Obama's, with no major foreign heads of state in attendance. But it did draw delegations from most of the 60 countries that had pledged to attend, despite the clouds of volcanic ash that shut down airports in Europe. Still, unlike the Washington summit, at which several deals on securing nuclear fuel stockpiles were announced, the Tehran conference yielded few concrete results. Instead, it served principally as a platform for Iranian attacks on U.S. nuclear policy in line with the disarmament requirements of the Nuclear Non-Proliferation Treaty (NPT).Ahmadinejad called on the U.S. to destroy its own nuclear arsenal and urged that all future nuclear disarmament talks be convened by countries like Iran, which have no nuclear weapons. "The involvement of the government of America will prevent any new treaty from being fair," he said. Supreme Leader Ayatullah Ali Khamenei, in a letter to the gathering, called the U.S. an "atomic criminal."It may not have stolen the limelight from Obama's event, but there was evidence at Iran's summit that Tehran's nuclear strategy is succeeding. Though U.S. officials say they have Russian and Chinese support for a new round of U.N. Security Council sanctions against Iran, Moscow and Beijing sent officials to attend Ahmadinejad's conference. And despite Washington's hopes for building Arab support for isolating and containing Iran, there were also delegations at the Tehran summit from Lebanon, which sits on the Security Council, and Iraq. Indeed, Baghdad's Kurdish Foreign Minister, Hoshyar Zebari, addressed the conference's opening session, blasting Israel, which is widely believed to have an undeclared arsenal of more than 200 nuclear warheads, for being the only nuclear armed country in the Middle East.Iran insists that its goal in enriching uranium is simply to develop the full fuel cycle of a nuclear energy program as allowed by the NPT. But the U.S. and its allies suspect Iran of using that energy program as cover to develop a nuclear weapons capability and want to end uranium enrichment on Iranian soil. Iran's failure to comply with all the transparency demands of the International Atomic Energy Agency have resulted in Security Council resolutions, backed by sanctions, demanding that it suspend uranium enrichment. But the West's determination to halt Iran's nuclear program has been a gift that keeps on giving to the Islamic Republic. Nuclear diplomacy initially prompted the U.S. to temper its criticism of the Tehran regime after it cracked down on post-election protests last year, and it helped the regime bolster its nationalistic credentials by standing up to foreign powers, which it accuses of depriving Iran of rights enjoyed by all other signatories of the NPT. Meanwhile, oil-rich Iran has relied on its commercial relations — especially with Russia and China — to thwart U.S. efforts to isolate Iran. Indeed, U.S. Secretary of Defense Robert Gates wrote a secret memo in January warning the Obama Administration that the U.S. has no effective policy for keeping Iran from building nuclear weapons if the regime decides to do so, the New York Times reported on Sunday. (Gates later suggested he was simply contributing to an "orderly" planning process for Washington's next steps in the effort to halt Iran's nuclear program.)Whether or not Iran's nuclear defiance will continue to pay political dividends at home remains to be seen. Though sanctions have been ineffective, the Obama Administration is hoping that new measures targeted at the interests of Iran's ruling class might drive a wedge between the government and the people, especially since the country's opposition movement — whose street protests have been suppressed by the government's readiness to use force — hopes to exploit Iran's growing economic troubles to broaden the base of opposition to the regime.But for now, the country's governing military and religious elite appear more unified behind the nuclear strategy than ever. Since the Obama Administration last week publicly changed its nuclear posture to forswear using atomic weapons on any country that doesn't possess nuclear weapons — but left open the possibility of using them against Iran and others it deems to be violating the NPT — Iranian politicians, clerics and generals have gone into rhetorical overdrive against the U.S. An Iranian general promised to vanquish all American soldiers in the Middle East should Iran be attacked. Israel, meanwhile, is threatening to stop Iran's nuclear program militarily if American diplomacy fails to do so — a scenario viewed as potentially disastrous by the U.S. military. And the Iranians are reviving talk of compromise — on their own terms, which wouldn't necessarily appeal to Washington — of a stalled deal to swap some of their uranium stockpile for reactor fuel. All of which leaves the Obama Administration with less room to maneuver in the nuclear impasse than Tehran.