Japan and Vietnam agreed Thursday to enhance bilateral cooperation on maritime security, criticizing China for increasingly assertive actions that have led to clashes between Chinese and Vietnamese vessels in the South China Sea.

"I am concerned about tensions in the region resulting from China's unilateral drilling activity," Prime Minister Shinzo Abe said at a meeting with Vietnamese Deputy Prime Minister Vu Duc Dam in Tokyo, according to the Japanese Foreign Ministry.

"Japan will continue to underscore the importance of observing law and being ruled by law," Abe said.