AP
With a vested interest in keeping the current Shi'ite government in power in Iraq, Iran has been happy to step up and provide support in its fight against Sunni insurgents of the Islamic State of Iraq and ash-Sham (ISIS).
It is a rare situation in which U.S. and Iranian interests align. A senior State Department official said diplomats from both countries held talks on Iraq on the margins of broader nuclear-program discussions in Vienna. The U.S. expects to work with Iran, though the State Department stressed there will be no military cooperation.
The sides are working to get a permanent Iranian nuclear deal by a July 20 deadline. Until now, that deadline was not expected to be met, with both sides looking toward a possible extension.
But both sides now have greater urgency toward a deal - President Barack Obama has desperately wanted a peaceful resolution to the Iran issue, and Iran now has more of an incentive to get its finances in order with turmoil and instability only growing in the region.
"They really want these sanctions off," Ian Bremmer, the president of Eurasia Group, told Business Insider. "They don't want to do anything in Iraq that could potentially scupper that deal.
"It's not that they'd trust U.S. military cooperation - after all, they're still on opposite sides on most other issues in the region (Lebanon, Israel, Syria, Egypt). But they're happy to open lines of communication and potentially even share some useful information tactically if that keeps them on track on the comprehensive nuclear deal."
The five world powers and Iran are meeting in Vienna this week in the latest round of talks aimed at a permanent solution to the country's nuclear program.
Jonathan Schanzer, a former terrorism finance analyst at the U.S. Department of Treasury, recently told Business Insider the Iraqi crisis plays "right into Iran's hand" at a time when it wants greater influence in the region.
"The ISIS crisis in Iraq plays right into Iran's hand," Schanzer, a former terrorism finance analyst at the U.S. Department of the Treasury, told Business Insider. "The regime in Tehran and the regime in Syria have been saying for months that they are the regional players that can help the West in its fight against terrorism. Despite the obvious irony - given the grisly terrorism track records of both countries - this may appeal to Washington, which is loathe to enter into new conflicts in the Middle East as it keen to 'lead from behind.'"
This attitude fits the foreign policy of the Obama administration, which has been increasingly reluctant to engage in Middle East conflict - and in conflict, in general. Amid the escalating crisis in Ukraine, Bremmer called this phenomenon - along with other countries' general disinclination - the "G-Zero order."
Bremmer told Business Insider the "G-Zero" phenomenon also applies to Iraq. And if the U.S. doesn't intervene, he said, no Western countries will.
"Absent American intervention, there's nobody else outside the region willing to make a serious effort here," he said. "And the Americans are hardly enthusiastic about intervention. Ukraine, Syria, Iraq - the severity of these conflicts are a direct consequence of the G-Zero."