GUANTANAMO BAY, Cuba — A military jury on Wednesday found a former driver for Osama bin Laden guilty of supporting terrorism but not of conspiring in terrorist attacks, handing the Bush administration a partial victory in the first U.S. war crimes trial in a half a century.

Jurors will reconvene today to determine his sentence.

The verdict, reached after about eight hours of deliberations over three days, only intensified the debate over whether Salim Ahmed Hamdan’s conviction was preordained in an unfair system — or whether military trials are appropriate for people accused of committing heinous acts against the United States.

The administration seized on the acquittal to defend its military justice system against accusations that it was politicized and drawn up to ensure convictions. Pentagon and White House officials said they are satisfied with the result.

“We’re pleased that Salim Hamdan received a fair trial,” White House spokesman Tony Fratto said. “The military commission system is a fair and appropriate legal process for prosecuting detainees.”

Despite the partial acquittal, Hamdan still faces up to life in prison.

With the conclusion of the trial — the first by military commission since the end of World War II — U.S. prosecutors can move ahead with military trials for up to 80 Guantanamo Bay detainees, including those accused of planning the attacks on the World Trade Center and the Pentagon. One reason Hamdan, who even the military judge labeled “a small player,” was tried first is so the system could be tested on him.

The six-member military jury found Hamdan guilty of supporting al-Qaida by driving and guarding bin Laden and ferrying weapons for the terrorist group. The jury found him not guilty of conspiring in terrorist attacks.

Hamdan, a Yemeni father of two, bowed his head and wiped his eyes with his white headdress as the verdict was read.

Even the prosecution’s own evidence portrayed Hamdan as someone who ferried weapons for al-Qaida and knew details of terrorist attacks, but only after they occurred and often based on conversations he overheard. One FBI agent testified that Hamdan emerged from training at an al-Qaida camp and said he had no interest in fighting.

“We were told that Guantanamo was necessary because these were the world’s most dangerous terrorists,” said Ben Wizner, an American Civil Liberties Union observer who criticized the Pentagon for revealing little about U.S. interrogation techniques. “Salim Hamdan is not one of the world’s most dangerous terrorists.”