The top commander of U.S. forces in the Asia-Pacific region reassured Tokyo on Thursday that Washington remains committed to the defense of Japan, amid concern that commitment may be weakening after an annual military exercise was canceled.

"The steadfast alliance between Japan and the United States is an enduring force for peace and stability in the Pacific region ... We remain committed to our mutual alliance, the defense of Japan," Adm. Philip Davidson, the head of the U.S. Indo-Pacific Command, told Prime Minister Shinzo Abe at their meeting in Tokyo.

Tokyo has been uneasy since the United States and South Korea announced this week the cancellation of the Ulchi Freedom Guardian exercise, which had been scheduled for August, fearing such a move could weaken the deterrence effect in the region provided by the U.S. military.