Prosecutors allege that Hassan Abu-Jihaad sent details of the location and vulnerabilities of a Navy battle group to suspected terrorism supporters in London when he was on active duty.
Abu-Jihaad is charged in the same case as Babar Ahmad, a British computer specialist arrested in 2004 and accused of running Web sites to raise money, appeal for fighters and provide equipment such as gas masks and night vision goggles for terrorists.
As Abu-Jihaad's trial started today. a British investigator testified that agents who searched Ahmad's parents house in 2003 found a computer floppy disk that authorities say contained details of ship movements.
Abu-Jihaad has pleaded not guilty to charges he provided material support to terrorists with intent to kill U.S. citizens. He also pleaded not guilty to charges he disclosed classified information relating to the national defense.