The Navy destroyer USS Lassen will sail within 12 nautical miles of artificial islands in the South China Sea to challenge China's territorial and maritime claims in the waters, a senior U.S. defense official said Monday. The Lassen could make its way to the Subi and Mischief reefs in the Spratly Islands as early as Tuesday, the official said, making it the first time a Navy warship has sailed within the territorial limit claimed by China for six reefs and shoals it has been building up into islands.