A mutual interest in a stable Iraq is driving Washington and Tehran - two otherwise increasingly antagonistic capitals - to sit down and talk.
Even as the Bush administration says America "may face no greater challenge from a single country than from Iran," and as US-backed efforts proceed in the United Nations Security Council to address Iran's nuclear ambitions, the two governments have agreed to meet in Baghdad.
The way forward for this conversation traverses a minefield of potential explosions, but the fact it is happening at all reflects a shift to pragmatic foreign-policy outlooks in both Washington and Tehran.
"No one knows how far this will go before it all blows up, or forces on one side or the other sabotage it, but it's another mark of the reemergence of realists in the Bush administration that we can even consider talking to the Iranians," says Daniel Brumberg, a professor of comparative government at Georgetown University in Washington.
In Iran, "efforts to talk to the US may well be the work of foreign ministry pragmatists [in Tehran] reasserting their influence" over the extremist stance of President Mahmoud Ahmadinejad, adds Mr. Brumberg. For these pragmatists, landing in the Security Council is the direct result of Mr. Ahmadinejad's confrontational antics, and they may see in Iraq a way to start undoing the damage.
The White House says the talks - the first acknowledged direct contacts between the two countries since discussions in 2003 on Afghanistan - will be limited in focus to Iraq. The US accuses Iran of providing support and materials to groups that have targeted American forces and interests in Iraq.
But the talks are also an acknowledgment of Iran's pivotal role in Iraqi affairs - political, social, and religious - at a particularly difficult moment for the US engagement there.
The US sought help from Iran after the US-led toppling of the Taliban government in Afghanistan. That experience ended up souring, but not before the Iranians took some constructive steps that aided the US goal of establishing a stable government, observers say.
One aim of Zalmay Khalilzad, the US ambassador in Iraq and the man authorized by President Bush to meet with the Iranians, will be to confront his interlocutors on the supplying of Shiite militias, a relationship the US says is exacerbating sectarian violence.
But Mr. Khalilzad - who was previously the US ambassador to Afghanistan - may venture into more political discussions, analysts say, encouraging the Iranians to use their extensive influence with some political leaders of Iraq's ruling Shiites to help in ending the damaging deadlock over forming a new government.
"The US says these talks will 'just be about Iraq,' but what does that mean?" asks Ray Takeyh, an expert in US-Iran relations at the Council on Foreign Relations in Washington. "Is it just rebuking them for their actions there, or is it, 'We don't want a civil war, and you don't, so how can we both work to avoid it?' "
The problem he sees is that the Bush administration rhetoric seems diametrically opposed to such an approach. "It might seem to make sense to talk to the Iranians about the mutual interests in a stable Iraq," he says. "But it would be inconsistent with everything else that the administration has been saying about the Iranians over the past two weeks: that they are our biggest single threat, and so on."
Mr. Takeyh says the Iranian regime is also motivated by a desire to undermine the deliberations about its nuclear program in the Security Council. "They may be betting they can lessen some of the pressure to act against them if they are seen to be engaging in something helpful like talks in Iraq," he says.
Some Iranian policymakers may be moved to demonstrate a willingness to cooperate with the Americans - who, after all, rid them of two of their archenemy neighbors, the Taliban and Saddam Hussein - both by the worrisome violence next-door and by a domestic population that wants desperately to avoid international isolation.
Iranian interests may not be identical to America's in Iraq, but growing prospects of a slide to full-blown civil war have rattled the Iranians, experts say. "The Iranians know that if the civil war accelerates they may be drawn into the swamp, and they don't want that," says Georgetown's Brumberg.
Still, actors on both sides could intervene to nip the talks before they even bud. "Will Ahmadinejad try to blow them up?" wonders Brumberg, who cites efforts already made to purge the foreign ministry.
And in the US, skeptics of such talks are surely watching for any missteps, he adds. "The Afghanistan experience" of talking with Iran "is actually a cautionary tale," Brumberg says. "It left a bitter taste, and some people are going to remember that."