James Petras is not simply a "liberal". He is an avowed Marxist.

James Petras, a retired Bartle Professor (Emeritus) of Sociology at Binghamton University, SUNY, New York, USA, and adjunct professor at Saint Mary's University, Halifax, Nova Scotia,Canada. He describes himself as a "revolutionary and anti-imperialist" activist and writer.
James Petras - Wikipedia, the free encyclopedia

A google search of his name turns up numerous articles pointing to his erroneous facts and figures, as well as others that refute his positions.
Breukelen advocaat Reviewed by Breukelen advocaat on . Are the Wars in Afghanistan and Iraq the Beginning of the End of the American Empire? By JAMES PETRAS Washington outlined in explicit language its plans to engage in sequential wars in the Middle East, Southwest and Northeast Asia and the Caribbean. Under the offensive military doctrine of 'Pre-emptive Wars' and the 'Global War against Terrorism', the United States' pursuit of military conquest was backed by Israel, Great Britain and several newly incorporated client states from Eastern Europe. The White House's grandiose scheme of world conquest was orchestrated and Rating: 5