U.S. patrols to raise stakes with Beijing in disputed South China Sea

Chinese dredging vessels are purportedly seen in the waters around Mischief Reef in the disputed Spratly Islands in the South China Sea in this still image from video taken by a P-8A Poseidon surveillance aircraft provided by the United States Navy in this May 21, 2015 file photo. REUTERS/U.S. Navy/Handout via Reuters

HONG KONG (Reuters) - U.S. plans to send warships or military aircraft within 12 nautical miles of China's artificial islands in the disputed South China Sea, possibly within days, could open a tense new front in Sino-U.S. rivalry.

A range of security experts said Washington's so-called freedom of navigation patrols would have to be regular to be effective, given Chinese ambitions to project power deep into maritime Southeast Asia and beyond.