Sometimes a wish can mobilize the will and power to make it come true. The Iraq Study Group (ISG) wishes the US could “engage directly with Iran and Syria in order to try to obtain their commitment to constructive policies toward Iraq and other regional issues.” Unfortunately, the US does not possess the types of power to force Iranian cooperation, and even if it did, Iran lacks the capacity to grant America’s wish in Iraq. Still, the Study Group has done a service by making it obvious that the US should not reject dialogue with Iran as a matter of principle.

The ISG assumes that Iran’s “interests would not be served by a failure of U.S. policy in Iraq that led to chaos and the territorial disintegration of the Iraqi state.” This is neither entirely right nor wrong. Possible US failure in Iraq can take several forms besides territorial disintegration, and Iranian actors may welcome lesser failures. Multiple factions tussle incessantly in Iran’s power circles; some will always resist cooperation with the US and pursue tactics to weaken it

Iraq is not the only arena of Iranian interest, nor is it the one where Tehran feels it needs to change its position most. Iran is more interested in winning recognition as the major power of the greater Middle East and gaining acceptance of its uranium-enrichment and plutonium-production programs. To make this happen, Iran wants the US to change its policies, not vice versa.

The ISG glides over the trade-offs that the US, Iran and other international actors would have to make to achieve win-win results. Henry Kissinger offered a realistic assessment in “The Washington Post,” noting that Iran “has no incentive to appear as a deus ex machina to enable America to escape its embarrassments, unless the United States retains an ability to fill the vacuum [left by an exit from Iraq] or at least be a factor filling it in.” Iran must be disabused of the idea that “it is able to shape the future [of the region] on its own.” But Kissinger, like the ISG, doesn’t specify how Washington can realistically scare or entice Iranian decision-makers into accommodating US desires.

The ascendant, militant Revolutionary Guard cohort represented by President Mahmoud Ahmadinejad feels no need to change. For them, instability in Iraq reduces the capacity of the US to force regime change in Iran and raises the international political costs of military action. The Iranian populace looks to Iraq and says, “If this is what regime change and democratization bring, no thank you.” The world has no tolerance for another US military adventure that would spike energy prices and foster more terrorism. Tehran concludes that the UN Security Council, thanks largely to Russia, lacks the will to impose the sorts of sanctions that stimulate internal debate over the costs versus benefits of continuing a nuclear program in defiance of international mandates. Iran’s bellicose confrontation with Israel – rhetorically and through support of Hezbollah, Hamas and Islamic Jihad – garners popular support among Sunni Arabs, lifting Iran’s claim to represent the Muslim world.

Iranian tough guys think Washington asks for favors in Iraq that Iran has no need to grant. Moreover, Iranian leaders know that they have less capacity to control the multiple Shiite actors in Iraq than the ISG assumes. Cooperating with Washington would expose this fact, thereby reducing perceptions of Iranian power.

Indeed, agreeing to cooperate with Washington in Iraq might expose Iran to unwanted recriminations when sectarian violence continues. Washington would inevitably accuse Iran of perfidy, setting back the cause of normalizing relations that cooperation might augment. Better to leave the mess in Washington’s hands.

Despite the anger it will inevitably provoke, Iranian coyness could be a blessing in disguise. Washington should think twice about whether changing Iran’s actions toward Iraq will improve international security as much as modifying Iran’s nuclear program or ending its material support of groups that practice violent politics in Lebanon and Palestine. Iran will not “give away” changes in any area. It will be most inclined to trade some indecisive help in Iraq for accommodation of limited-scale uranium enrichment on Iranian territory, while insisting that Iran has neither the right nor the capacity to control Hezbollah, Hamas and Islamic Jihad.

To avoid such trade-offs, the US and international community need greater power to exacerbate Iranian vulnerabilities in response to Iranian defiance or alleviate them in response to Iranian cooperation. None of the country’s neighbors can be truly said to like Iran, even if the Arab “street” celebrates when revolutionary personalities spit in the face of Israel and the US. The European Union, Russian, Chinese, Indian and other governments that deal with Iran generally find the experience exasperating. Iran’s neighbors and outside powers want it to be contained. The problem is they don’t trust the US to do it effectively and don’t want to be seen cooperating with an American government loathed for its support of unjust Israeli expropriation of Palestinian property in the West Bank and East Jerusalem, as suggested by Steven Erlanger in “The New York Times” in November.

The Iranian economy cannot sustain a clerical regime that fails to produce meaningful employment opportunities for educated youth. Inflation and deficits rise while politicians squander oil revenues including the subsidizing of Hezbollah in Lebanon. With the current economic structure enriching the Revolutionary Guard and clerical establishments, neither is eager to embrace the opening to the international economy that the US and Europe offer as potential reward. But even if Iranian leaders did embrace integration with the global economy, it would bring pain in the short term, while the gains are beyond the horizon of current officials. Such political expedience ultimately will be the downfall of the clerical regime, and the weakness should be exploited through explicit and de facto international sanctions. Yet, the lure of international economic cooperation to change Iranian behavior is not as great in the short term as the US and the EU would like.

None of this argues against direct dialogue and a willingness to explore trade-offs with Iranian decision-makers. However, Iran is no more likely to cooperate than the Bush administration did in 2002-2003 when Iran reached out to it. Ideological American leaders tragically and arrogantly overestimated their power then; Iran’s deluded bellicose leaders appear likely to do the same now.

There is, however, a cost-free way to test whether dialogue might be productive. President Ahmadinejad has written two open letters to President Bush and the American people, in May and late November. While their contents have been dismissed as unworthy of response, these letters should be taken as a bid for dialogue. If Bush were to proffer an eloquent response, exploring themes of international justice, Sunni-Shiite accommodation and the illegality of Iran’s defiance of the Security Council’s nuclear resolution, a dialogue would commence. The most difficult first step requires no negotiation. Global expectations would rise for continuation. Ahmadinejad gambles that his words increase Iran’s soft power and leverage, but ultimately his esoteric extremism rings hollow. The US should articulate the justness and practicality of the UN Security Council’s positions on Lebanon, the nuclear issue and terrorism in a dramatic correspondence for the world to read.

Iran does have weaknesses, and a dialogue can expose them, perhaps intensifying the country’s internal fissures. Refusal to talk cedes the high ground to Iran without any benefit to Washington.

George Perkovich is vice president for studies at the Carnegie Endowment for International Peace and co-author of “Universal Compliance: A Strategy for Nuclear Security.”