By Dana Feldman

RIVERSIDE, California (Reuters) - Four California men accused of plotting to join al Qaeda militants for training in Afghanistan appeared together in federal court for the first time on Wednesday and pleaded not guilty to charges they conspired to support terrorists.

The Afghan-born accused ringleader, Sohiel Omar Kabir, 35, was captured in Afghanistan last month, a day after three younger co-defendants were arrested by federal agents outside of Los Angeles.

The group, all U.S. citizens or permanent residents, are accused of planning to unleash a campaign of "violent jihad" against U.S. military forces and other Americans overseas, in a case based largely on the work of a paid FBI informant.

Kabir, who served in the U.S. Air Force about a decade ago, is accused recruiting two co-conspirators to join him for training with al Qaeda and the Taliban in Afghanistan, according to an FBI criminal complaint.

The FBI says those two men, Ralph Deleon and Miguel Alejandro Santana Vidriales, converted to Islam under Kabir's influence before he left Southern California to travel abroad in 2011. They are in turn alleged to have enlisted a third man, Arifeen David Gojali, in September.

Those three accused co-conspirators, all men in their early 20s, were arrested together in Chino, California, on November 16, two days before the FBI says they had planned to fly from Mexico to Turkey en route to join Kabir.

Each of the four is charged with a single count of conspiracy to provide material support to terrorists, which carries a maximum penalty of 15 years in prison.

All pleaded not guilty on Wednesday during a hearing in Riverside, east of Los Angeles, that lasted less than five minutes after their cases were merged in a superseding indictment, and a tentative trial date was set for August. Continued...