[5][6] The Alex Boncayao Brigade was established in May 1984 and was named after a labor leader killed by Philippine government security forces the year before.

The brigade became especially active after the departure of then-President Ferdinand Marcos as a consequence of the People Power Revolution, and during the term of President Corazon Aquino.

In 1993, Filemon Lagman and several cadre of the Manila-Rizal regional committee of the Communist Party of the Philippines (CPP) broke away from the mainstream group, taking the Alex Boncayao Brigade with them.

Nilo dela Cruz, using the alias "Sergio Romero", was arrested that same year in Bulacan after crashing his car while being pursued by government intelligence agents.

[9] In 2003 it was reported that Dela Cruz had "shifted from terrorist activities as leader of the ABB to organizing the labor forces of the Philippines into trade unions".

[6] In 1996, the ABB also claimed responsibility for the assassination of Philippine Constabulary Lt. Col. Rolando Abadilla, a former chief of the Metrocom Intelligence and Security Group during the Marcos dictatorship.

[1] Terrorist incidents attributed to the Alex Boncayao Brigade in the Global Terrorism Database show that the majority of their acts are armed assault and assassinations.

[15] This in turn prompted a vehement condemnation from Filemon Lagman; in a press release he branded Tabara and Dela Cruz "scoundrels masquerading as revolutionaries".