Manila, which has a mutual defence pact with Washington, has been engaged in months of confrontations with Beijing over disputed areas of the South China Sea.
Beijing claims almost the entirety of the crucial waterway, despite an international ruling that its assertion has no merit.
United States Defense Secretary Pete Hegseth visited Manila last week and said that “friends need to stand shoulder to shoulder to deter conflict to ensure that there’s free navigation” in the South China Sea.
At this month’s Balikatan exercises, US and Philippine troops will conduct a “full battle test” of “all of the plans, all of the doctrines, all of the procedures that (they) have developed in the past years”, Brawner said.
“It’s very important that we prepare for any eventuality,” he added.
Brawner alleged that “communist China is already conducting united front works in our country”.
“They are already infiltrating our institutions, our schools, our businesses, our churches, even our ranks in the military,” he said without giving details.
He said the Philippines was also experiencing “cyber warfare, information warfare, cognitive warfare, political warfare”.
The Chinese embassy did not immediately respond to requests for comment.
The Philippines has in recent weeks made a series of arrests of Chinese suspects accused of conducting surveillance on military camps and Filipino naval and coast guard ships.
