MANILA, Philippines — Hundreds of American and Filipino troops concluded Monday a new combat exercise in the northern Philippines that tested their endurance in more than a week of brutal heat and volatile weather, and braced them to respond to any threat in tropical jungles and on scattered islands, two US and Philippine generals said.

The Biden administration has been strengthening an arc of military alliances in the Indo-Pacific to better counter China, including in any possible confrontation over Taiwan and other Asian flash points. The move has dovetailed with Philippine efforts to shore up its territorial defenses amid escalating disputes with Beijing in the South China Sea.