The Pentagon admitted that its guided missile destroyer USS Decatur sailed close to the Paracel Islands held by China on Oct. 21.

By U.S. Navy photo by Mass Communication Specialist Seaman Gary Prill (RELEASED) [Public domain], via Wikimedia Commons

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One U.S. official said the patrol did not cross the 12-mile territorial limit of any of the feature and was carried out to challenge claims in the Paracels.