MANILA » U.S. and Philippine forces opened joint combat exercises under some uncertainty on Tuesday, days after the Philippines’ new leader said they would be the last such drills of his six-year presidency.

Marine commanders from both sides said at the opening ceremony that the exercises, involving 1,100 American and 400 Filipino military personnel, are aimed at improving readiness by the two countries to respond to a range of crises while deepening their historic ties.

Angered by U.S. criticism of his deadly anti-drug campaign, President Rodrigo Duterte said last week that the maneuvers would be the last of his term, which began in June. His foreign secretary later said the decision was not final, sparking questions as to whether other annual U.S.-Philippine military exercises would proceed as planned.

U.S. Embassy officials said Washington has not been formally notified by the Philippine government of any move to scrap other planned drills. Such a move by the Philippines would impede Washington’s plans to expand the footprint of U.S. forces in Southeast Asia to counter China.

A Philippine military spokesman for the ongoing exercises, Capt. Ryan Lacuesta, sidestepped the question of whether Duterte’s remarks have affected the troops and the atmosphere of the drills, partly staged to improve camaraderie between the two combat forces.

“As much as I would like to answer that question, I would leave that to higher authorities,” Lacuesta said Tuesday.

U.S. Marine Brig. Gen. John Jansen said that aside from promoting regional security, the exercises have helped save lives in terms of fostering more rapid and organized responses to disasters like the deadly 2013 devastation wrought by Typhoon Haiyan in the central Philippines.

Citing a much-awaited drill that involves American and Filipino marines wading ashore in an amphibious beach landing and in boat raids, Jansen said the exercise “is not just about projecting power from the sea, it is about growing a capability.”

Duterte, who describes himself as a leftist leader, has had an uneasy relationship with the United States, a key treaty ally. He has said he is charting a foreign policy not dependent on the U.S., and has taken steps to revive ties with China that had been strained under his predecessor over long-standing territorial conflicts.

Duterte has announced publicly that he will not allow the Philippine navy to conduct joint patrols with the U.S. military in the disputed South China Sea because it could spark an armed conflict in Philippine territory. He has also said he wants U.S. forces out of the southern Philippines, where he said minority Muslims resent the presence of American troops.

Still, Duterte has said he will not abrogate a 1951 Mutual Defense Treaty with the U.S. and will maintain the long alliance with America.