Iraqi Kurdish troops have been working with American ground and air force personnel since the early 1990s and have developed a close and often innovative battlefield relationship. To the Americans the Kurds are the most trusted Iraqi troops they work with but because of Iraqi government pressure the U.S. cannot supply the Kurds with the special radios and other equipment needed to enable qualified Kurds to call in American air strikes. This is because the Iraqi government is dominated by Iraqi Shia Arabs who are, in turn, heavily influenced by Shia Iran. Iraq, Iran, Turkey and Syria do not want their Kurdish minorities to get too strong and then unite to form an independent Kurdish state.
To the Arabs the Kurds display many annoying characteristics. For one thig the Kurds are far less corrupt, especially when it comes to military matters and particularly when it involves the Americans and other Western nations that provide training and aid.
As a result of all this the Kurds and Americans have developed informal but highly effective methods to provide U.S. air support to more Kurdish units. This is done by identifying those Kurdish troops (usually veteran officers and NCOs) who know how to identify and describe (to trained air controllers) targets for an air strike. These improvised air controllers use their cell phones and an improvised security system to contact a local joint (U.S.-Kurdish) headquarters where Kurdish speaking American (sometimes Kurdish-Americans) air controllers handle contact with the bombers overhead and pass on the target coordinates.
Both the American and Kurdish troops recognize that Kurdish ground troops with prompt American air support are one of the most effective weapons available against ISIL (Islamic State in Iraq and the Levant) in Iraq. The Iraqi government tolerates this arrangement because Kurdish forces are vital for pushing ISIL out of Mosul and the Kurds have promised that their troops will be withdrawn once the Iraqi army and militia forces are in control of the city. The offensive is supposed to take place by mid-2016, a year later than originally planned. Everyone understands that the offensive will not work without the help of the Kurds.