Most important, no major shift has occurred in Iran’s attitude toward the United States and the P-5+1 negotiating group. In spite of Obama’s Persian New Year address to Iran, the Iranians did not change their attitude toward the United States. The unrest following Iran’s contested June presidential election actually hardened the Iranian position. Mahmoud Ahmadinejad remained president with the support of Supreme Leader Ayatollah Ali Khamenei, while the so-called moderates seemed powerless to influence their position. Perceptions that the West supported the demonstrations have strengthened Ahmadinejad’s hand further, allowing him to paint his critics as pro-Western and himself as an Iranian n...

Most important, no major shift has occurred in Iran’s attitude toward the United States and the P-5+1 negotiating group. In spite of Obama’s Persian New Year address to Iran, the Iranians did not change their attitude toward the United States. The unrest following Iran’s contested June presidential election actually hardened the Iranian position. Mahmoud Ahmadinejad remained president with the support of Supreme Leader Ayatollah Ali Khamenei, while the so-called moderates seemed powerless to influence their position. Perceptions that the West supported the demonstrations have strengthened Ahmadinejad’s hand further, allowing him to paint his critics as pro-Western and himself as an Iranian nationalist.

But with September drawing to a close, talks have still not begun. Instead, they will begin Oct. 1. And last week, the Iranians chose to announce that not only will they continue work on their nuclear program (which they claim is not for military purposes), they have a second, hardened uranium enrichment facility near Qom. After that announcement, Obama, British Prime Minister Gordon Brown and French President Nicolas Sarkozy held a press conference saying they have known about the tunnel for several months, and warned of stern consequences.

This, of course, raises the question of what consequences. Obama has three choices in this regard.

First, he can impose crippling sanctions against Iran. But that is possible only if the Russians cooperate. Moscow has the rolling stock and reserves to supply all of Iran’s fuel needs if it so chooses, and Beijing can also remedy any Iranian fuel shortages. Both Russia and China have said they don’t want sanctions; without them on board, sanctions are meaningless.

Second, Obama can take military action against Iran, something easier politically and diplomatically for the United States to do itself rather than rely on Israel. By itself, Israel cannot achieve air superiority, suppress air defenses, attack the necessary number of sites and attempt to neutralize Iranian mine-laying and anti-ship capability all along the Persian Gulf. Moreover, if Israel struck on its own and Iran responded by mining the Strait of Hormuz, the United States would be drawn into at least a naval war with Iran — and probably would have to complete the Israeli airstrikes, too.

And third, Obama could choose to do nothing (or engage in sanctions that would be the equivalent of d...

Second, Obama can take military action against Iran, something easier politically and diplomatically for the United States to do itself rather than rely on Israel. By itself, Israel cannot achieve air superiority, suppress air defenses, attack the necessary number of sites and attempt to neutralize Iranian mine-laying and anti-ship capability all along the Persian Gulf. Moreover, if Israel struck on its own and Iran responded by mining the Strait of Hormuz, the United States would be drawn into at least a naval war with Iran — and probably would have to complete the Israeli airstrikes, too.

And third, Obama could choose to do nothing (or engage in sanctions that would be the equivalent of doing nothing). Washington could see future Iranian nuclear weapons as an acceptable risk. But the Israelis don’t, meaning they would likely trigger the second scenario. It is possible that the United States could try to compel Israel not to strike — though it’s not clear whether Israel would comply — something that would leave Obama publicly accepting Iran’s nuclear program.

And this, of course, would jeopardize Obama’s credibility. It is possible for the French or Germans to waffle on this issue; no one is looking to them for leadership. But for Obama simply to acquiesce to Iranian nuclear weapons, especially at this point, would have significant diplomatic and domestic political ramifications. Simply put, Obama would look weak — and that, of course, is why the Iranians announced the second nuclear site. They read Obama as weak, and they want to demonstrate their own resolve. That way, if the Russians were thinking of cooperating with the United States on sanctions, Moscow would be seen as backing the weak player against the strong one. The third option, doing nothing, therefore actually represents a significant action.