Emphasize "nearly." If you were the Iranian mullahs, you'd want this radicalization of the Iraqi Shia to keep going. The Iraqi Shiite community is still far from replicating the Iranian revolutionary pattern, where the Revolutionary Guards gradually replaced local militias, establishing themselves as the guarantor of the revolution's success. There are many things about Iraq that are different from revolutionary Iran, that Tehran's mullahs know are unchangeably different, but the one thing that the clerical regime surely sees as indispensable is the need to keep Iraq unsettled. With violence, Sistani and the moderate clergy will continue to collapse and the Americans will bleed.
Tied down and fearful in Iraq, the Iranians now gleefully note, the Americans will continue to lose spirit and be unable to challenge the mullahs' nuclear-weapons program and their designs in the Middle East. The Sunni-Shiite collision in Iraq doesn't fit with Tehran's ecumenical drive to become the leader of the militant Muslim world. The regime, rhetorically led by the lay but ideologically die-hard Ahmadinejad, will compensate by continuing to ratchet up its anti-American and anti-Zionist message. But Iran's ruling mullahs will not compromise the radicalization of the Shia in Iraq--a huge success for them, far greater in its potential consequences than the radicalization of the Lebanese Shia under Hezbollah--for the sake of reaching out to the Arab world's Sunni militants outraged by Iraqi Shiite attacks against Iraqi Sunnis. Since 1979, Arab Sunnis have regularly disappointed Iran's Islamists. Tehran will play for the far greater gain of destroying and then rebuilding Iraq's Shiite clergy. Although American realists cherish the belief that states hate a vacuum and disorder, stability in Iraq is the last thing Tehran wants to see now.
Let's note a historical contrast. Realists like to cite the international conference on post-Taliban Afghanistan as an instance of a positive Iranian role in the region. However, Iranians were not "cooperating" because they wanted to be helpful. In 2003, the clerical regime's fear of the United States was palpable. Iranians had watched the United States wipe out the Taliban to the east and Saddam to the west. Tehran was focused on the superpower on its doorstep and an American president who'd demonstrated, unlike his predecessors, that he would invade Middle Eastern countries that posed a threat to the United States.
They were also "helpful" because, truth be told, the Iranians really don't care strategically about their eastern neighbor. Iran's Islamic revolution has been overwhelmingly aimed westward toward the Arabs and the United States. Afghanistan has been for the clerical regime, as it was for the Shah, a backwater. What the Iranians have wanted most from post-Taliban Afghanistan is the exit from Iran of Sunni Afghan refugees, whom Iranians see as disreputable elements engaged in crime and the seduction of poor Shiite Persian women. Many realists like to use Iran's relatively benign behavior in Afghanistan as proof of Tehran's good intentions and what might be possible in Iraq. They shouldn't. For Tehran's ruling clergy, the radicalization of Iraq's Shia is worth fighting for.
So what does the United States have to offer the Iranian clergy that might tempt them to compromise their interests in Iraq? Well, there's the bomb. However, this, too, makes no sense. There is zero chance the president would allow these negotiations. Besides, an American promise not to interfere in Tehran's nuclear-weapons program would mean nothing since the mullahs now think they've already won, in great part because they believe--and the U.S. media, prominent realists, and much of the Democratic party reinforce the view--that America is too enfeebled by Iraq, too fearful of possible Iranian retaliation inside the country, for the Bush administration seriously to challenge Iran's nuclear aspirations.
With the exception of its own survival, there is nothing the clerical regime cares more about than the bomb. If the United States wanted to persuade the mullahs to stop supplying money and weaponry to radical groups in Iraq, then a true realpolitician would threaten the regime's most cherished plans--its nuclear program. Yet in the Gates-Brzezinski colloquy on Iran, Gates conceded a nuclear weapon to the clergy. This is an odd position to take before even trying to enter into "negotiations."