Philippine and U.S. troops have begun annual joint exercises that are smaller in scale than in years past, focusing on disaster response and counterterrorism while excluding territorial defense operations.

The changes were instructed by President Rodrigo Duterte who has said he wants to chart a foreign policy less oriented toward Washington while expanding security ties with China and Russia. He has taken a softer stance than his predecessor on the territorial disputes with China in the South China Sea.

Opening rites for the "Balikatan" or "Shoulder-to-Shoulder" exercises were led Monday by Defense Secretary Delfin Lorenzana and U.S. Ambassador Sung Kim at the Philippine military's headquarters in metropolitan Manila.

Officials say 5,400 personnel will be involved in the drills, or about half of 11,000 troops who took part last year.