As Chinese ships fired water cannons at Philippine vessels in the South China Sea in November 2021, Beijing's then-ambassador to Manila asked Filipinos on Facebook to share their favorite things about China.

Among the hundreds of gushing responses were three from a young man named "Vince Dimaano.”

His comments — like many responding to the Chinese Embassy’s posts — weren’t genuine. They came from fake accounts paid for by the diplomatic mission, according to internal documents from a Manila-based marketing agency.