The court also handed down jail terms ranging from six to 15 years for two other men convicted in the conspiracy, which began with the killing of Laurence Foley, 60, an Amman-based administrator for the U.S. Agency for International Development. Foley was gunned down outside his Amman home on Oct. 28, 2002.
Col. Fawaz Buqour, the court's president, acquitted the 11th defendant, Numan al-Hirsh, saying there was no evidence to implicate him in the conspiracy.
The guilty verdicts can be appealed.
Among those sentenced to death was Jordanian militant Ahmed al-Khalayleh, better known as Abu Musab al-Zarqawi, who is thought to be a close associate of al Qaeda chief Osama bin Laden. Al-Zarqawi was among six defendants who were tried in absentia; his whereabouts are unknown.
U.S. officials have offered a $10 million reward for al-Zarqawi's capture, saying he is trying to build a network of foreign militants in neighboring Iraq to work on behalf of
al Qaeda, which is blamed for the Sept. 11 attacks.
The five defendants in custody, standing in the dock wearing dark blue prison uniforms, shouted "allahu Akbar," or "God is great," and "this verdict is unfair" as Buqour read the verdict in a small courtroom guarded by military policemen armed with machine guns.
Outside the courtroom, a military helicopter hovered overhead during the hearing.
The U.S. Embassy issued a statement thanking Jordan for "bringing those responsible for Larry's murder to justice." The statement vowed to "remain resolved to continue his (Foley's) work to improve the lives of ordinary Jordanians and to bring the people of our two nations closer together."
Jordan, a moderate Arab nation with close ties to the United States and a peace treaty with Israel, has been the target of several terror plots.
Foley's death was the only attack linked to the Jordan conspiracy, which allegedly targeted unspecified American and Israeli interests in Jordan.
Eleven Libyan, Syrian, Palestinian and Jordanian men had been charged in the conspiracy. Their trial began in the military State Security Court 10 months ago.
The five in custody - Salem bin Suweid, Yasser Freihat, Mohammed Amin Abu-Saeed, Numan Al-Hirsh and Mohammed De'mes - had pleaded innocent. They told the court their guilty confessions had been extracted under duress.
Bin Suweid and Freihat also had produced witnesses who testified the men were not at the crime scene when Foley was killed.
Military prosecutors charged bin Suweid, 41, with firing the gun that killed Foley, and Freihat, 29, with driving the getaway car. Bin Suweid and Freihat were sentenced to death, as were all six fugitives: al-Zarqawi, Palestinian Shaker Yousef al-Absi, Jordanian Moamar Ahmed al-Jaghbeer and Syrians Mohammed Ahmed Tayourah, Ahmed Hussein Hassoun, Mahmoud Abdul-Rahman Thaher.
De'mes was given 15 years with hard labor.
Abu Saeed, a Jordanian of Palestinian descent, was initially sentenced to 15 years in jail with hard labor, but Buqour immediately commuted it to six years, saying he wanted "to give this young man another chance" and that it was not believed he had been deeply involved in the terror plot.
The government has blamed Foley's killing on bin Laden's al Qaeda network. Prosecutors did not mention al Qaeda in the initial indictment, but said at least half of the suspects had links with al-Zarqawi, who allegedly provided bin Suweid with weapons and $62,000 to finance the plot.
The indictment said bin Suweid began recruiting militants to his cell in Syria in 1997. He came to Jordan late in 1999, using a forged Tunisian passport bearing the name "Ali Lafi." Automatic machine guns, explosives and detonators had been smuggled from Iraq in batches starting in June 2002.
Earlier, 22 Islamic extremists were convicted of plotting to attack U.S. and Israeli tourists using bombs and poison gas during Jordan's millennium celebrations. The plot, in which al-Zarqawi also allegedly was involved, was foiled in November 1999 and blamed on bin Laden.
By Jamal Halaby