[1] A one-time follower of Lyndon LaRouche,[2] Tarpley is known for his role in the 9/11 truth movement, believing 9/11 was a false flag operation.

Since March 2006, Tarpley has hosted a weekly online talk show called World Crisis Radio,[9] broadcast by GCNLive.com.

Tarpley maintains that the September 11 attacks were engineered by a rogue network of the military-industrial complex and intelligence agencies as a false-flag operation.

[16] On January 21, 2015, Tarpley was interviewed by Guns and Butter's Bonnie Faulkner about "geopolitical terrorism and the destabilization of governments and how others like Russia and Belarus are responding".

[17][18] Tarpley is a member of the "world anti-imperialist conference" Axis for Peace, of Scholars for 9/11 Truth and of a research Netzwerk of German 9/11 authors founded in September 2006.