The USS Milius conducted a freedom of navigation operation in the South China Sea near the Parcel Islands.
The freedom of navigation operation challenged the restrictions on innocent passage imposed by China, Taiwan, and Vietnam.
It also challenged China's claim to straight baselines enclosing the Parcel Islands.
The Parcel Islands are claimed by China, Vietnam, and Taiwan.
The Chinese government protested the operation, saying it violated their sovereignty and security and breached international laws.
The U.S. sees China's straight baselines around the islands as a violation of international sea law.
The incident highlights ongoing tensions between the U.S. and China in the South China Sea.
The USS Milius was conducting an exercise with the Japan Maritime Self-Defense Force before conducting the freedom of navigation operation.