U.S. concerned about Iraq-Iran cooperation

Iranian Defense Minister Hossein Dehghan and Iraqi Defense Minister Irfan al-Hiyali met Sunday in Tehran to sign a military agreement aimed at improving joint efforts to curb the influence of jihadis such as the Islamic State.

ISIS has conducted deadly attacks in both countries and is still being fought by Iraq with support from Iran and the U.S., but the U.S. has become increasingly concerned about Iran's growing foothold in Iraq.

Despite the volatile history of the two majority Shiite-Muslim neighbors and their differing views on Washington, the new deal will reportedly see Iran and Iraq's armed forces work together on a number of strategic levels.