By David Morgan
WASHINGTON (Reuters) - The United States on Monday urged China to observe international maritime rules after the Pentagon said five Chinese ships, including a naval vessel, harassed a U.S. Navy ship in international waters.
The Chinese vessels "shadowed and aggressively manoeuvred in dangerously close proximity" to the USNS Impeccable on Sunday, with one vessel coming within 25 feet (7.6 meters) of the U.S. ship, a Defence Department statement said.
The American ship, an unarmed ocean surveillance vessel with a crew of civilian contractors, was conducting routine operations in the South China Sea 75 miles (120 km) south of Hainan Island, the Pentagon said.
"Our ships operate fairly regularly in international waters where these incidents took place," White House spokesman Robert Gibbs told a news conference.
"We are going to continue to operate in those international waters and we expect the Chinese to observe international laws around them."
The U.S. embassy in Beijing lodged a weekend protest with the Chinese government, State Department spokesman Robert Wood said. U.S. defence policy officials on Monday also reiterated the protest to China's defence attache in Washington.
"The unprofessional manoeuvres by Chinese vessels violated the requirement under international law to operate with due regard for the rights and safety of other lawful users of the ocean," Pentagon spokesman Marine Corps Major Stewart Upton said in a statement.
"We expect Chinese ships to act responsibly and refrain from provocative activities that could lead to miscalculation or a collision at sea."
The encounter was the latest incident of "increasingly aggressive" Chinese conduct in the area, which in recent days also included fly-bys of U.S. Navy ships by Chinese maritime surveillance aircraft, the Pentagon said.
The Pentagon identified the Chinese vessels in Sunday's incident as a navy intelligence ship, a bureau of maritime fisheries patrol vessel, a state oceanographic administration patrol vessel and two small Chinese-flagged trawlers.
The Impeccable is one of six Navy surveillance ships that gather underwater acoustical data while operating as part of the U.S. Military Sealift Command, the Pentagon said.
The Chinese vessels surrounded the Impeccable while two closed to within 50 feet (15.2 meters), waving Chinese flags and telling the U.S. ship to leave the area, the Defence Department said.
The Impeccable responded by spraying one of the vessels with fire hoses and later informed the Chinese ships by radio that it was leaving the area and requested a safe path to navigate, it said.
Two of the Chinese vessels stopped directly in front of the U.S. ship and dropped pieces of wood in its path.
The Pentagon described accounts of half a dozen other incidents dating back to March 4, in which the Impeccable and its sister vessel, USNS Victorious, were subjected to aggressive behaviour, including dozens of fly-bys by Chinese Y-12 maritime surveillance aircraft.
On March 7, a Chinese intelligence collection ship challenged the Impeccable over the radio, calling her operations illegal and directing the vessel to leave the area or "suffer the consequences," the Pentagon said.
Two days earlier, a Chinese frigate approached the Impeccable and crossed its bow twice, once at a range of 100 feet (30.4 meters).
(Additional reporting by Ross Colvin, Andrew Gray and Paul Eckert; Editing by Paul Simao)