Washington, Sep 7 (IANS) American warplanes continued their air strikes on the Sunni militant organistion Islamic State (IS) in northern Iraq Friday and Saturday, destroying some of its military vehicles, the US Central Command said.

A mix of attack, fighter and remotely piloted aircraft were used to conduct two air raids in support of operations near Irbil, capital of Iraq's autonomous Kurdish region, Xinhua quoetd the Central Command as saying in a statement.

It said four Humvees, one armoured personnel carrier and two trucks, with one carrying a mounted machine gun, were destroyed in the air attacks, while another Humvee and one truck were damaged.

"The strikes were conducted under authority to protect US personnel and facilities, support humanitarian efforts, and support Iraqi forces that are acting in furtherance of these objectives," the command said.

The US warplanes have conducted a total of 133 air strikes in northern Iraq since Aug 8.

Washington said Friday that it had built a "core coalition" to combat the Islamic State in Iraq, whose fighters had seized vast swathes of territory in northern Iraq since June and announced the establishment of a caliphate in areas under its control in Syria and Iraq.

Addressing a press conference as NATO wrapped up a summit in Wales Friday, US President Barack Obama vowed to "degrade and ultimately defeat" the group, which had beheaded two American journalists.