In the first verdict in the terror trials held at Guanatanamo Bay, a military jury on Wednesday convicted Osama bin Laden's former driver for providing material support to terrorism but tossed out a more serious charge of conspiracy.
Salim Ahmed Hamdan faces a maximum sentence of life in jail as his trial now goes into the sentencing phase.
The Pentagon-selected six-member jury reached a split verdict after deliberating for eight hours over three days.
The Yemeni national's trial, the first before the special tribunals created by President George W Bush to try suspects in the "war on terror", was being seen as a crucial test of the controversial military commission system.
The White House was quick to react, saying that Hamdan received a "fair trial".
During the two-week-long proceedings, Justice Department prosecutor John Murphy described Hamdan as an al-Qaeda warrior. "He has wounded, and the people he has worked with have wounded the world," Murphy told the jury.
The defence tried to make the point that Hamdan was only a driver for Osama bin Laden and not in any higher position in the al-Qaeda leadership.
"We will capture or kill Osama bin Laden some day. You should not punish the general's driver today with the crimes of the general," his court-appointed military attorney, Navy Lieutenant Commander Brian Mizer, told the court.