To preserve the car-and-sprawl economy of the US, it is necessary to spend a lot of money controlling energy sources and transport routes, especially oil. A big reserve of high net-energy oil is in Kirkuk, Iraq. Consequently the US has to fight the Islamic State (aka ISIS) for control of this oil. It would be a lot easier just to make buses free and gradually dismantle sprawl, but a lot of billionaires would lose money, so they force the taxpayer to continue this subsidy.
ibtimes : "Of the $1.1 billion, more than $60 million have been spent on Navy munitions alone, which include 47 Tomahawk cruise missiles fired by American warships from the Red Sea and the Persian Gulf. The bulk of these missiles targeted al Qaeda-linked Khorasan group near the Syrian city of Aleppo, AP reported. The figures released by the U.S. Central Command reportedly did not provide a cost estimate for ammunitions used by the Air Force, which is expected to be significantly higher."