The helicopter gunships were initially deployed to Baghdad International Airport to provide protection for US military and diplomatic facilities.
Until Sunday, when Apache helicopters were used in Anbar Province west of Baghdad, US airstrikes have been limited to Air Force and Navy fighter jets and drones.
The use of attack helicopters opens up new capability in the US-led campaign against ISIL, which the Obama administration insists would not entail “boots on the ground.”
A defense official confirmed to ABC News that the helicopters were used to carry out airstrikes on ISIL targets northeast of Fallujah.
They “struck two mortar teams, a large ISIL unit and two small ISIL units,” according to a press release by US Central Command.
The attacks were conducted in coordination with Air Force fighter aircraft that supported the operation.
ISIL militants made swift advances in much of northern and western Iraq over the summer, after capturing large swaths of neighboring Syria.
In recent weeks, ISIL militants have attacked several cities in Anbar, bringing them closer to Iraq’s capital.
US President Barack Obama authorized airstrikes on ISIL targets in Iraq in mid-August.
Five European countries-- Belgium, Denmark, the Netherlands, Britain and France-- have committed aircraft to the military campaign. But so far only Britain and France have participated in the airstrikes.