As 2009 draws to a close, President Barack Obama is expected to take stock of his diplomatic overture to Iran. He will not be able to avoid the conclusion that his approach so far has achieved next to nothing: Iran continues to progress, without consequences, toward military nuclear capability. The one hope for a breakthrough agreement - the nuclear fuel deal offered in October - was dashed when Iran not only rejected the deal, but responded with further defiance: President Mahmoud Ahmadinejad announced Iran's intent to build 10 additional uranium enrichment facilities. Moreover, the UN Security Council's permanent members are not in agreement on moving to harsher economic sanctions.

Does this mean that the diplomatic track is hopeless? Not yet. What it does mean is that diplomacy and negotiations are anything but easy to carry out. And if the United States is truly serious about diplomacy, that seriousness must be apparent in its own approach, and then brought into play in its interactions with Iran.

Some assume that diplomacy is synonymous with a softer approach to international challenges, one that focuses on engagement and reassurance rather than more forceful confrontation. But that isn't the case here, because the Americans have undertaken to convince Iran to back down from a goal that it is highly motivated and determined to achieve. This means that the diplomatic process must be a game of hardball. The fact that it will be a "war" of words rather than a military struggle does not imply that any less determination, focus and resolve will be required of the United States if it is to succeed.

Perhaps ironically, the developments of 2009 put America in a better position to pursue tough diplomacy in two important respects. First, evidence of Iran's military ambitions has mounted. Serious questions and concerns about the nature of the country's activities are coming from the International Atomic Energy Agency itself; of particular note is the "secret annex" to its reports on Iran - details of which were leaked to the press over the summer. To this one must add the revelation of the enrichment facility near Qom; Mohamed ElBaradei's lamentations before leaving the IAEA over the "dead end" reached with Iran; and the recent Times of London report on Iranian work on a neutron initiator since 2007. The upshot of this is that the 2007 U.S. National Intelligence Estimate has been rendered virtually obsolete, and the burden of proof is now on those who continue to adhere to the view that Iran's intentions are not military.

The second point regards the role of "confidence building" in U.S.-Iranian relations. Confidence-building measures are an important diplomatic tool when states have developed a common interest to cooperate, but are unable to do so because of deep-seated tensions in their relations. They work when both sides are dependent on the other to achieve a mutually desired result. This is not the U.S.-Iranian dynamic. While relations are certainly characterized by tension, the two states lack the common interest to cooperate - at least according to the current framing of the nuclear issue. Iran's unwillingness to cooperate is not due to tensions with the United States, but rather to the fact that the cooperation demanded by the latter simply doesn't serve Iran's perceived interest. This was made clear in 2009, especially surrounding the proposed fuel deal. The foremost challenge for the United States, thus, is not to build confidence, but to demonstrate resolve while formulating the contours of a deal that Iran also has a clear interest in pursuing.

This means that the United States must not waste any more time trying to negotiate interim deals with Iran that are devised either to test whether its intentions are peaceful, or to build confidence. It should be focused on the final deal, which it should negotiate with Iran bilaterally. As long as the P5+1 countries (the nuclear powers - the United States, Russia, France, the U.K. and China - plus Germany) are not on the same page with regard to Iran, the multilateral format weakens their collective ability to confront it with the necessary determination.

The United States must also find a way to communicate true resolve to Iran. Projecting the idea that there is no realistic scenario in which the United States would use military force is counterproductive in this regard, as are indications that Afghanistan and Pakistan are much higher on the American agenda than Iran, and hints that the United States could successfully contain a nuclear Iran.

As Iran gets closer to its goal, it is becoming bolder in its willingness and demonstrated ability to challenge the international community. It could still become interested in negotiating a deal with the United States, but only if a common interest is created, and if there are real consequences for failing to negotiate seriously. Only the United States can fulfill the role of the determined bilateral negotiator. But if the message it conveys is that it lacks the political will to make Iran a top diplomatic priority, or if it shies away from the bilateral format and clear demonstration of its resolve - then diplomacy doesn't stand a chance.

Emily B. Landau is senior research fellow and director of the Arms Control and Regional Security Program at the Institute for National Security Studies (INSS).