WASHINGTON (AP) - Arizona Sen. John McCain is calling for the United States to lead an international effort to begin air strikes on Syria.

McCain says that the Syrian government's brutal crackdown on its opponents has resulted in war crimes and that its neighbors in the region will intervene militarily, with or without the U.S. From the Senate floor on Monday, McCain said the United States has a moral and strategic obligation to force out President Bashar Assad and his loyalists.

Last month, McCain urged international cooperation to help supply the anti-Assad rebels with weapons and other aid. At the time, he stopped short of endorsing direct U.S. military involvement.