US Defense chief affirms commitment to protecting Turkey

Turkey's Prime Minister Binali Yildirim, right, shakes hands with U.S. Secretary of Defense James Mattis, ahead of the Somalia Conference, in London, Thursday, May 11, 2017. (Prime Minister's Press Service, Pool Photo via AP) (The Associated Press)

U.S. Secretary of Defense James Mattis listens during a National Security session at the 2017 Somalia Conference in London, Thursday, May 11, 2017. The Somalia Conference is aimed at improving stability and prosperity in Somalia and boosting the humanitarian response to the drought. (AP Photo/Kirsty Wigglesworth) (The Associated Press)

In this Tuesday, May 9, 2017 photo, Turkey's Prime Minister Binali Yildirim, sits at a helicopter gunship, during a visit at IDEF'17, the International Defence Industry Fair in Istanbul, Turkey. Yildirim on Wednesday, May 10, 2017, has spoken out against a U.S. decision to arm Syrian Kurdish fighters which Turkey regard as terrorists, saying it cannot use one terror organization to try and defeat another terror group. (Hakan Goktepe/Prime Minister's Press Service, Pool Photo via AP) (The Associated Press)

U.S. Defense Secretary Jim Mattis has reaffirmed the U.S. commitment to protecting Turkey at a meeting with the Turkish prime minister in London.

It's the first meeting of the officials since the Pentagon announced the U.S. would arm Syrian Kurds in the fight to oust Islamic State militants from the group's stronghold in Raqqa.

A Pentagon spokesperson says both leaders affirmed their support for peace and stability in Iraq and Syria.

Turkey is deeply opposed to the arms agreement and has called for its reversal.

Turkey believes the U.S.-backed Syrian Kurds, known as the YPG, are terrorists. But the U.S. is convinced they are the most effective local fighting force against IS.

Turkey's prime minister said Wednesday the U.S. can't use one terrorist group to fight another.