A Philippine court convicted 14 Muslim militants Thursday and sentenced them to life in prison for abducting a U.S. missionary couple and 18 others in a 2001 kidnapping spree that left one of the missionaries and another American dead.

The case prompted Washington to start training Filipino troops.

Most of the top leaders of the Al Qaeda-linked Abu Sayyaf group, which orchestrated the abductions at a resort island, have been killed in clashes since the trial opened in 2003. Philippine officials have credited the U.S. counterterrorism training that started in 2002 for many of the battlefield successes.

Americans Gracia and Martin Burnhams, missionaries for the Florida-based New Tribes Mission, were celebrating their 18th wedding anniversary when they were snatched by the Abu Sayyaf at the upscale Dos Palmas resort on Palawan island on May 27, 2001, and taken by speedboat to southern Basilan island.

Fellow American Guillermo Sobero and 17 Filipinos also were kidnapped. Sobero, from Corona, Calif., was among several hostages beheaded by the rebels. Martin Burnham and a Filipino nurse were killed during a military rescue raid on June 7, 2002.

The other hostages were released or managed to escape.

"We commend the justice system for showing the rule of law," said Robert Courtney, the U.S. Justice Department's attache at the Manila embassy. He said he will relay the decision to Gracia Burnham, who was wounded in the rescue.

Former Filipino hostage Angelica Montealegre praised the convictions.

"They deserve this, she said, although she cautioned that some guerrillas remained at large and she still felt in danger.

Defendant Toting Hannoh, who was found guilty, struck a defiant note. Asked if this was the end of the Abu Sayyaf, he said: "No, it will become stronger."

Out of 85 suspects originally charged with kidnapping, 23 were captured and tried, and 18 appeared in court.

Four were acquitted Thursday. Four others were killed in a botched prison break in 2005, and one has been cleared of charges.

Among those acquitted was the only woman in the group, Star Till, the disabled sister of rebel leader Abu Serbia, who was killed by troops after the abductions.

"I'm so happy. Thanks to Allah! I'm taking my daughter home," said her mother, Assure Churning. "She was never a terrorist."

Burnham, from Wichita, Kan., returned to the Philippines in 2004 to testify against her captors. She told the court she learned from Abu Serbia that the rebels received a ransom from an unknown source, but that the guerrillas still refused to free her and her husband.

Burnham recounted her ordeal in a book, "In the Presence of My Enemies," which aroused controversy in the Philippines because of her allegations that an unnamed Filipino general tried to get half of a possible ransom for the hostages and that soldiers delivered food and sold weapons to the guerrillas.

A year after the resort raid, the U.S. military began sending troops and instructors to train Filipino soldiers in counterterrorism.

U.S.-backed offensives had dislodged the guerrillas from their bases on Basilan, but they have remained a major threat and continued to regroup. Officials estimate their number is down to about 300 guerrillas from about 1,000 in 2001.

The overall leader, Khadaffy Janjalani, was killed last September in fighting on southern Jolo island. His presumed successor, Abu Sulaiman, was shot dead in a separate clash earlier this year.