FILE PHOTO: Hua Chunying, spokeswoman of China's Foreign Ministry, speaks at a regular news conference in Beijing, China, January 6, 2016. REUTERS/Jason Lee

BEIJING (Reuters) - China’s Foreign Ministry on Tuesday said it has expressed deep concern to the United States after Washington sent two warships through the Taiwan Strait in the second such operation this year.

Ministry spokeswoman Hua Chunying made the comments at a daily news briefing in Beijing.

China claims democratic and self-ruled Taiwan as its own.