The chairman of the Senate Armed Services Committee and a senior Republican are urging President Barack Obama to use limited military force to end the two-year civil war in Syria.

Michigan's Democratic Sen. Carl Levin and GOP Sen. John McCain of Arizona wrote the president Thursday, calling for air strikes against the Syrian regime's aircraft and creation of a safe zone inside Syria's northern border.

The two lawmakers said Patriot missile batteries already deployed to southern Turkey could be positioned to protect the zone, if Turkey agreed.

Levin and McCain also pressed for greater aid to vetted opposition groups, including tactical intelligence, food, medicine, fuel and communications equipment.

Citing conflicting reports about chemical weapons, the two wrote Obama that Syria under President Bashar Assad is disintegrating.