US President Barack Obama and Turkish Prime Minister Recep Tayyip Erdogan are vowing to increase pressure on Syria's President Bashar al-Assad to step down.

Obama and Erdogan appeared in a news conference at the White House.  The President said that the only way to resolve Syria's two-year civil war was for Assad to hand over power to a transitional government.

"We both agree that Assad needs to go,'' said Mr. Obama adding that Turkey would play a critical role in that process.

Erdogan's visit to Washington came two days after suspected Syrian car bombs exploded in a southern Turkish village, killing dozens.  The village is the home of some of the 400,000 Syrian refugees who went to Turkey to escape the fighting.