U.S. authorities have charged four men, including one who served in the U.S. military, with plotting to kill Americans overseas by joining al-Qaida and the Taliban,.

The Federal Bureau of Investigation said late Monday the group was planning to engage in “violent jihad” with bombings of military bases and other government facilities.

The FBI says that in 2010, Sohiel Omar Kabir, a naturalized U.S. citizen originally from Afghanistan, introduced two of the men to the radical Islamic doctrine of cleric Anwar al-Awlaki, who was killed last year by a U.S. drone strike in Yemen. Authorities say Kabir served in the Air Force in 2000 and 2001.

Investigators say the men later recruited the fourth man, and Kabir traveled to Afghanistan where he planned to arrange meetings with terrorists.

Kabir is being held in Afghanistan. The other three men — a U.S. citizen, and U.S. residents born in Mexico and the Philippines — are in federal custody in the western U.S. state of California.

Each defendant faces up to 15 years in federal prison if convicted.