The U.S. State Department said Friday it was not cooperating with Iran in the fight against the Islamic State of Iraq and Syria, although a spokeswoman for the department said the U.S. would not rule out "engaging Iranians," after reports emerged Iran's Supreme Leader had cleared the elite Quds Force to cooperate with the U.S, Al Arabiya reported.
Citing unnamed sources in Tehran, the BBC's Persian Service had reported that Ayatollah Ali Khamenei had given the order directly to Qassem Solemani, the head of the Quds Force, which forms part of the larger Islamic Revolutionary Guard Corps.
Also on Friday, the U.S. announced the formation of a 10-member international coalition to support the Iraqi government in its fight against the militants, although the new group ruled out sending ground troops into the embattled country.
In contrast, there have been reports of Iranian forces' presence in Iraq for months, and the Islamic Republic's leaders have repeatedly vowed to step in to protect Iraqi Shi'ites and their holy places from the advance of extremist Sunni ISIS militants.
However, these are the first reports that the Supreme Leader, who has the last word in military and foreign affairs decision-making in Iran, has cleared military cooperation with the United States on the issue.
A video that emerged on Thursday allegedly shows Solemani among a group of Iranian fighters seen celebrating the recapture of the Iraqi town of Amerli from ISIS militants on August 31, according to reporting by Le Monde and France 24.
Persian news website Entekhab.ir also released a photograph of Solemani standing next to a young fighter that it said was taken in Amerli.
That town, 160 kilometers (miles) north of Baghdad, was liberated from a months-long siege at the end of August by Iraqi military forces joined by Shiite and Kurdish fighters.
Having had extremely rocky relations since the Islamic Revolution overthrew the U.S.-backed Shah in 1979, the two countries are currently involved in tense negotiations aimed at ending a longstanding dispute over Iran's controversial nuclear program.
Iran usually opposes U.S. involvement in Iraq.