The U.S. military plans to send the USS Lassen destroyer within 22 kilometers (12 nautical miles) of China's artificial islands in the South China Sea, according to a U.S. official speaking to VOA Monday.
The official said it is "unclear when this will occur," but that execution of the plan could be within hours.
The destroyer, likely partnered with a surveillance plane, will patrol near reefs in the Spratly archipelago, according to the official.
China has warned it will not allow any country to violate the airspace of the Spratly archipelago, which was submerged before China began a major construction project to make them into islands in 2014.
The U.S. cites international law in its stance that artificial reefs do not entitle a country to a territorial water claim. The U.N. Convention on the Law of the Sea states that "artificial islands, installations and structures do not possess the status of islands" and "have no territorial sea of their own."
The patrol, when it occurs, will mark the most serious U.S. challenge to China's claim of territorial sovereignty around the islands. The U.S. has patrolled in the South China Sea, but never this close to the Spratly archipelago.
The Navy has conducted similar patrols near artificial territories built up by the Philippines and Vietnam, according to Pentagon officials.
"We conduct freedom of navigation operations to challenge excessive maritime claims on a regular basis around the world," Pentagon spokesman Navy Capt. Jeff Davis told reporters Monday.
The South China Sea is home to one of the world’s busiest shipping routes, so U.S. interests would be directly affected if China were to enforce control over the sea.