U.S. Defense Secretary Jim Mattis says Turkey's ground and air offensive against a Kurdish enclave in northwestern Syria is distracting from international efforts to ensure the defeat of the Islamic State group.

Mattis said it also risks worsening the humanitarian crisis there and in other parts of Syria.

He said the U.S. sympathizes with Turkey's security concerns, given that it has an active Kurdish insurgency inside its borders. He said the renewed violence in the Afrin region of Syria could be exploited by IS.

Mattis commented to reporters traveling with him in Indonesia, where he had meetings Tuesday with senior government officials. He called the meetings positive and said they discussed ways to increase U.S. military education and training for members of the Indonesian military, including their special forces troops.