Last week Secretary of State John Kerry announced that the deadline for negotiations over Iran’s nuclear program would once again be pushed back. Extending the talks keeps in place a year-old agreement that has halted Iran’s drive toward a bomb while negotiators pursue a comprehensive agreement. The agreement provides for several steps that rollback Iran¹s bomb effort, including diluting medium-enriched uranium, halting work on a nuclear reactor, and allowing inspectors enhanced access to nuclear facilities. By all indications, Iran has so far complied with the agreement admirably.

However, some observers oppose continuing the talks and are calling for additional sanctions against Iran. For instance, Sen. Marco Rubio wasted no time in saying, “we need to once again increase the pressure on Iran.” Similarly, Senators John McCain, Lindsey Graham and Kelly Ayotte released a joint statement after the extension was announced, which stated in part: “We believe this latest extension of talks should be coupled with increased sanctions and a requirement that any final deal between Iran and the United States be sent to Congress for approval.”

This would be a mistake. Applying more sanctions would eliminate any hope for a deal, leading to two results: it would pave the way for a nuclear Iran and shatter American credibility on future nonproliferation efforts.

Patience and prudence have rarely been features of American nonproliferation policy. The fact of the matter is that American credibility for adhering to its end of a nonproliferation agreement has suffered, particularly in the complex negotiations over the North Korean program. In the late 1990s and early 2000s, North Korea repeatedly proved willing to delay and degrade its nuclear program in exchange for energy and food aid, recognition, and security assurances.

Yet the Bush administration could not summon the patience and forbearance to pay this pittance; hardliners within the administration stubbornly undermined any and all progress. Each time talks collapsed, North Korea made more progress toward their weapon program. In 2006, the White House refused to compromise over the timing of providing the North with a safeguarded, proliferation-proof light water reactor, and the hermit kingdom responded by testing a nuclear device. By the time the administration came around to diplomacy in its second term, it was too late.

There is no guarantee that continuing negotiations would have prevented a North Korean bomb, but the administration did not have an alternative strategy that could. Instead, hardliners engaged in wishful thinking and indulged their general distaste for difficult diplomacy. The confused and inconsistent American engagement with North Korea allowed them to develop a nuclear weapon.

Much like the North Koreans, the Iranians have been obdurate and highly suspicious negotiators. They seem intent on rejecting reasonable offers and frequently make alarming statements. At times, it seems they could only want a bomb. Yet the Obama administration¹s approach to Iran has shown a consistency, patience, and prudence that is unique among counterproliferation efforts.

The administration understands that a deal with Iran is still the best and only hope for ending its nuclear ambitions, and is still very much in American interests. A deal would improve the global economy, stabilize the region, and pave the way for a freer Iran. Importantly, a deal would also improve America’s larger nonproliferation goals.

As long as nuclear weapons exist, nonproliferation will remain a vital U.S. national interest. There will be future nuclear aspirants and future negotiations. The Bush administration policies in Iraq and North Korea were devastating to American credibility on nonproliferation. If the United States continues to scrap the deals it negotiates, it will soon find it has no leverage over countries considering a nuclear program.

By contrast, the Iran talks can help generate leverage on nonproliferation if they can demonstrate the efficacy of novel mechanisms. Although the sides rightly refuse to discuss details of the negotiations in public, there are two such provisions under consideration. The first would require Iran to ship much of its uranium to Russia, where it would be enriched and converted into fuel rods suitable for Iranian power plants. This would allow Iran to meet its power needs while retaining less domestic enrichment capability.

The second provision would allow inspectors broad latitude to take environmental samples across Iranian territory to search for the radioactive isotopes that inevitably leak out of clandestine nuclear facilities. The measures may go even beyond the Additional Protocol, an International Atomic Energy Agency (IAEA) standard that gives inspectors greater latitude to search for undeclared nuclear facilities, which the United States and the IAEA are encouraging states to accept.

Both measures could not only help resolve the negotiations over the Iranian program, but could serve as important tools in the future. If Iran accepts these provisions, other states may as well.

Skeptics of the talks are right to say that the United States has little leverage over Iran, but this is how credibility and leverage is created for the future. And with important global nuclear meetings coming up next year (including on the Nonproliferation Treaty), it is a very poor time to show that the United States cannot negotiate credibly on nuclear issues.

Having started negotiations, the United States should finish them. Reaching a deal will not only restrain the Iranian nuclear program, but could help restrain others in the future. As frustrating as it is, Congress is going to have to summon the patience to let diplomacy work. Applying additional sanctions may feel cathartic for congressmen like Sen. Rubio, but only a deal can end the Iranian nuclear program.

Adam Mount Stanton Nuclear Security Fellow The Council on Foreign Relations.

Image: Flickr/International Campaign to Abolish Nuclear Weapons/CC by-nc 2.0