Does diplomacy with Tehran have a good chance to resolve the Iranian nuclear threat? The Obama administration thinks so, which is why Washington has doubled down on an interim agreement with the Iranian regime that provides it with substantial sanctions relief. But a recent fiasco concerning Iran’s aborted role in talks over Syria’s civil war presents a significant reason for doubt about the president’s strategy: Iranian diplomats frequently use talks to get what they want without making any substantive concessions to their counterparts.

The debacle with Syria unfolded in the wake of continuing opposition by the Obama administration to congressional efforts to strengthen sanctions on Iran should negotiations fail. In fact, White House Press Secretary Jay Carney suggested that supporters of sanctions were advocating “a march to war,” and that negotiations with Iran held the potential for “a peaceful solution that prevents Iran from obtaining a nuclear weapon.” But Iranian leaders may not view diplomacy in quite the same way — and the case of Syria illustrates why.

Since the United States and its allies are largely unwilling to use force to drive Syrian dictator Bashar al-Assad from power, global powers are trying to end the civil war through negotiations that include both the Assad regime and Syrian opposition forces. Many world leaders, including United Nations Secretary-General Ban Ki-moon, believed the success of talks depended on including Assad’s closest ally: Iran.

Therefore, Ban — reportedly with the support of U.S. Secretary of State John Kerry — tried to secure Iran’s participation in talks that would take place in Geneva. But to ensure that Tehran would not exploit its attendance by attempting to obstruct diplomatic progress and thereby strengthen Assad, the Obama administration conditioned Tehran’s presence on its support for a 2012 international agreement known as the Geneva Communiqué, which calls for a new government in Syria.

In private talks with Iranian Foreign Minister Mohammad Javad Zarif, Ban reportedly thought he had secured Iran’s oral agreement to endorse the Geneva Communiqué. Then, as the talks approached, Ban rushed to invite Iran to attend the negotiations — only to see Tehran fail to support the Geneva Communiqué in public. Ban’s spokesman said that the “oral understanding” that Iran had given to Ban “was to be followed by a written understanding. That didn’t happen.” The U.S. was embarrassed, the Syrian opposition was outraged and threatened to stay away from the talks, and Ban, under U.S. pressure, withdrew Iran’s invitation.

Tehran exploited its adversaries’ diplomatic weakness by using the well-worn tactic of offering private promises one day and failing to deliver the next. As the Obama administration and Ban’s team apparently failed to stay on the same page tactically, Ban swallowed Iran’s bait and provided the regime with the legitimacy of an invitation to the talks, thinking that Iran would follow through on its promises. Iran pocketed the legitimacy and then pulled the rug out from under Ban and the U.S. by refusing to publicly commit to the Geneva Communiqué. The United States and the U.N., looked naïve and incompetent, while Iran — after years of increasing international isolation for its pursuit of nuclear weapons and sponsorship of terror — was able to portray itself as the aggrieved party.

Iran’s skilled outmaneuvering of its interlocutors–over mere negotiations over an invitation to other negotiations — raises a troubling question: Why should we assume that, when the stakes are much higher for all sides, America will successfully be able to use diplomacy to convince Iran to abandon its nuclear weapons ambitions?

The Obama administration continues to negotiate with Iran, and perhaps it should. However, when considering when to talk — and when to stop talking and step up the pressure — policymakers should recognize not only that diplomacy is unlikely to succeed in addressing the Iranian threat, but that it has real perils. These perils include the risk of the unacceptable—but very possible — outcome that Tehran will exploit negotiations to outsmart its diplomatic adversaries, escape the grasp of sanctions, and become a nuclear weapons state.