The Iranian government made a huge move toward rapprochement today, with Supreme Leader Ayatollah Ali Khamenei saying that he approved of cooperation with the United States in fighting ISIS, and that he had already authorized the Iranian military to coordinate with the US, as well as Iraqi and Kurdish forces in the fight.

Iran views ISIS as a major threat, and the group is actively fighting wars against two of their key allies, Iraq and Syria, and forming a nation out of those territories quite successfully. As ISIS gets closer to the Iranian border, the nation is more willing to work with any possible allies in countering the Islamists’ expansion.

Offers for rapprochement are rare, but the US reaction is common: outright rejection. The State Department insisted that the US was neither going to do any coordination with Iran, nor even share information on their operations.

The US has made it clear they want to insinuate themselves into the ISIS war in a big way, and assemble a massive “coalition of the willing” for the war, though they likewise have been unwilling to accept the most likely such allies, Iran and Syria, because of a longstanding policy of hostility toward those nations.