The United States and Iran have a “mutual interest” in defeating the Islamic State (ISIS) group, Secretary of State John Kerry said on Wednesday, AFP reported.

He stressed, however, that the long-time foes are not cooperating to do so.

“They are totally opposed to ISIL and they are in fact taking on and fighting and eliminating ISIL members along the Iraqi border near Iran and have serious concerns about what that would do to the region,” Kerry told lawmakers, referring to ISIS by another acronym.

“So we have at least a mutual interest, if not a cooperative effort,”  he added.

Kerry stressed, however, that the United States had not asked Tehran to get involved in the fight against ISIS.

There have been speculations in recent months of military cooperation between the United States and the Islamic Republic.

In September, Kerry ruled out Iran’s participation in a global coalition against ISIS, only to backtrack on that position several days later and saying he would be open to military cooperation with Iran.

Around the same time, there were reports that Iran’s Supreme Leader, Ayatollah Ali Khamenei, had approved cooperation with the U.S. in the fight against Islamic State.

Iran’s foreign ministry said the report was not correct, and the State Department later clarified that Washington has “no plans” for any military coordination with Iran in the fight against ISIS.

In December, Kerry also denied there was any military coordination with Iran, after the Pentagon said that Iranian jets had deployed against ISIS fighters in eastern Iraq.