A U.S. Navy warship neared an artificial island built by Beijing in the South China Sea on Wednesday, the first challenge of China’s territorial claims conducted under the Trump administration. Officials who spoke on the condition of anonymity told Reuters the USS Dewey came within 12 miles of the Spratly Islands, which are a matter of territorial dispute between China and other countries in the region. Under international law, territorial waters extend to 12 miles from the coastline, meaning the U.S. Navy’s maneuver is considered a direct challenge to China’s territorial claim. The move comes as President Trump seeks the help of Beijing in reining in North Korea’s nuclear and missile activities. But the maneuver appeared to send a signal to Beijing that the U.S. agrees with a ruling by a court in the Hague last year that found China’s claims to large portions of the South China Sea were invalid. The last such freedom-of-navigation operation was conducted under then-President Barack Obama in October.