One of the first steps was apparently training, such as shown in this file video.
A criminal complaint unsealed yesterday accuses three of the men of planning to leave the United States for training under Al-Qaida and the Taliban.
The F-B-I field office in Los Angeles says the men told an informant that they intended to carry out "violent jihad."
Among their potential targets were American military personnel overseas.
Three of the suspects are men in their early twenties.
The complaint paints a trail to a fourth man, who is accused of introducing the others to various extremist material, including radical and violent Islamic doctrine.
That man was arrested in Afghanistan.
All four are charged with conspiracy to provide material support to terrorism.
If convicted, they would face a statutory maximum penalty of 15 years in federal prison.