Ray Takeyh is a senior fellow at the Council on Foreign Relations.

The Iran nuclear negotiations have reached a stalemate. The White House has asked for an extension, and Congress should give it additional time. But the latest stumble offers an occasion for some searching questions. Is the best we can hope for a series of interim agreements that curb Iran’s program but do not resolve the fundamental issues? Is our coercive strategy sufficient for dealing with a revolutionary state on the march in the Middle East? Can Iran’s nuclear ambitions even be affected by diplomatic mediation?

The international community has been negotiating with Iran over its illicit nuclear program not for six months but for 11 years. Along the way a variety of justifications have been offered for the lack of progress in the talks. Initially, when Germany, France and Britain led the discussions, it was suggested that only U.S. participation could produce a resolution. When the United States joined the so-called P5+1 delegation under the Obama administration, it was claimed that only bilateral talks could break the deadlock. However, Iran’s dogmatic negotiator at that time, Saeed Jalili, usually abjured such encounters and was thus easily blamed for the impasse. If only Iran were governed by a pragmatic president and represented in the bilateral talks by a subtle diplomat who spoke the language of moderation. Then came the election of Hassan Rouhani and the appointment of Foreign Minister Mohammad Javad Zarif, which yielded a modest interim agreement — and yet another deadlock.

There was always something peculiar about segregating Iran’s nuclear pretensions from the region’s raging conflicts. Iran’s supreme leader, Ayatollah Ali Khamenei, has been busy fortifying the Assad dynasty in Syria, ensuring that a pliable regime remains in power in Iraq, nurturing Hezbollah and arming Hamas as it wages war against Israel. In Khamenei’s telling, the United States is a crestfallen imperial state unable to impose its mandates on a defiant region. In a recent speech, he mocked the notion of U.S. military retribution, declaring, “There are very few people in today’s world who take these military threats seriously.” Whatever confidence-building measures his diplomats may be contemplating, Iran’s most consequential decision-maker sees in America’s retreat a rare opportunity to project power in a contested Middle East. Nuclear weapons capability is central to the ambitions of an aspiring hegemon.

It is indisputable now that in the last round of talks the United States did not possess sufficient leverage to impose a settlement. The existing sanctions regime has been effective in isolating Tehran from the global markets, but more obviously needs to be done. It is time for the White House and Congress to come together and craft a bipartisan sanctions bill that further stresses Iran’s economy. The notion that congressional action would derail an accord is no longer a suitable argument. What prevented an agreement in Vienna was not congressional initiative but Iranian truculence.

Tehran, IRAN: Iran's supreme leader Ayatollah Ali Khamenei speaks to Iranian Air Force commanders in Tehran. (-/AFP/GETTY IMAGES)

In considering its response, the United States would be wise to complement its sanctions policy with a determined regional strategy of pushing back against Iran and negating its considerable recent gains. This requires a reengagement with the region and its many crises. By aiding reliable rebels in Syria and helping rehabilitate an inclusive order in Iraq, the United States could go a long way toward blunting Iran’s surge. An Islamic Republic that is isolated in the region and economically exhausted at home may yet prove to be a constructive arms-control interlocutor. In the absence of such measures, the White House should be asked to explain why it perceives that the next four months will be different than the past six or, for that matter, the preceding 11 years.

The Obama administration faces a fork in the road. It can reengage in the Middle East with an eye toward tempering Iran’s power, but this would require making a substantial commitment to a region whose conflicts and tribulations it would prefer to leave behind. Or it can dispense with deadlines and grandiose objectives and settle for a diplomacy of incremental steps and limited gains. Interim agreements would thus no longer be a pathway to a final accord but an end in of themselves. Such are the travails of a superpower in an age of retrenchment.