HANOI (Reuters) - Philippine President Rodrigo Duterte plunged one of the United States' most important Asian alliances deeper into uncertainty on Wednesday by declaring upcoming U.S.-Philippines military exercises "the last," and ruling out any joint navy patrols.
The firebrand Duterte pledged to honour a longstanding security treaty with the United States, but said China opposed joint marine drills in the Philippines starting next week and there would be no more war games with Washington after that.
"I am serving notice now to the Americans, this will be the last military exercise," Duterte said during a visit to Vietnam. "Jointly, Philippines-U.S.: the last one."
Duterte's remarks gave one of the strongest signs yet of fissures in a historic alliance that Washington has relied upon as it tries to cement its influence in Asia to counterbalance China's rapid rise. Duterte's foreign minister later said his comments had been taken out of context.
State Department spokesman John Kirby said he was not aware of any official notification from the Philippines about ending joint exercises.
"Our focus is on the relationship today and moving it forward," Kirby told a regular news briefing. "We continue to believe that that's possible. ... (W)e have significant security commitments with the Philippines. We're committed to meeting those commitments and to furthering this relationship."
The Philippines military and U.S. Marines are to hold annual amphibious landing exercises from Oct. 4 to 12. Military leaders from the countries have also started preparing for a new set of exercises next year.
Duterte said he would establish "new alliances for trade and commerce" with Russia and China, but would maintain security agreements with Washington.
His near-daily outbursts against the United States began in earnest last month, when he spoke of alleged atrocities a century ago by the United States when it was the Philippines' colonial ruler.
He has called President Barack Obama a "son of a bitch" and said he would order the pullout of the remaining U.S. special forces stationed in the Philippines' restive south.
Duterte told a gathering of the Filipino community in Hanoi there would be no chance of naval patrols with Washington because they risked dragging the Philippines into conflict with China.
The Philippines and China have long sparred over sovereignty in the South China Sea, and Manila and Washington have shared concerns about China's military clout and pursuit of broad maritime claims.
Asked if Duterte was serious about ending military exercises with the United States, Foreign Secretary Perfecto Yasay said he was misunderstood and his remarks taken out of context.
The only thing Duterte had ruled out were joint patrols beyond the Philippines' 12-nautical mile territorial waters, Yasay said.
"Our agreement, that will be respected and this is what the president clearly meant," Yasay told a scrum of reporters, referring to a 1951 Mutual Defence Treaty.
Despite Yasay's words, Duterte's latest comments add to uncertainty about what his end game is and whether Manila's next moves could complicate regional diplomacy or alter the status quo in the South China Sea.
A U.S. defence official said he had not seen the Philippines make a formal request to stop sea patrols and added that the bar for a "joint patrol" with the Philippines was low.
"If the joint patrols stop, will this have any sort of major impact on the situation in the South China Sea? Most likely not," the official said, speaking on condition of anonymity. He added that in a sign things were continuing as usual, the landing ship USS Germantown would be making a port call in Manila from Wednesday.
Richard Jacobson, an American security expert, said Duterte's posturing could embolden China to exploit a testy relationship between two old allies.
"The U.S.-Philippines relationship might become strained and even shaken," Jacobson said.
"The U.S. geopolitical stakes in the region are much too high to react to his hyperbole. The current attitude in Washington is mature - more of patience than feeling provoked."
The Philippines has not formally committed to joining the United States in patrols beyond its territorial waters in the South China Sea. It has carried out at least two patrols with the United States this year that remained within 12 nautical miles of the Philippine coast.
Additional reporting by Karen Lema and Manuel Mogato in Manila and David Brunnstrom and Idrees Ali in Washington; Editing by Alex Richardson and Leslie Adler