Ta Mok, the infamous one-legged military leader of the Khmer Rouge, was arrested last weekend in Cambodia. "The Butcher," as he is known, was one of the last holdouts from the guerrilla group. An unrepentant hardliner, Ta Mok commanded the loyalty of a dwindling band of insurgents, who were troublesome, but posed no real threat to the Phnom Penh government. Ta Mok has the distinction of being the only Khmer Rouge leader to have been captured by the Cambodian government, and the timing could not have been more convenient. Now, the government of Prime Minister Hun Sen has a scapegoat for the Khmer Rouge evils and a device to silence the growing call for an international trial of the Khmer Rouge. That plan must be thwarted.

The Cambodian government has said that it will try Ta Mok in a military court. The military-court system was subjected to international scrutiny -- and found wanting -- last year, when it tried former Prime Minister Norodom Ranariddh, ousted in a coup by Mr. Hun Sen in 1997, on charges of treason. Predictably, Mr. Ranariddh was convicted, then later pardoned by King Sihanouk. The proceedings were widely condemned as a show trial, manipulated by Mr. Hun Sen to allow him to hold national elections shortly afterward. Clearly, it is not the forum to deal with the grave issues raised by the crimes of the Khmer Rouge.

A panel of United Nations experts has recommended that the former Khmer Rouge leaders be tried for genocide and crimes against humanity. The report followed a request in 1997 by Mr. Ranariddh and Mr. Hun Sen, who were then serving as Cambodia's two co-prime ministers, to set up an international tribunal to try the leaders of the guerrilla movement that killed nearly 2 million people during its four years in power. Mr. Ranariddh, whose party is now part of the government, supports the panel's recommendation. Mr. Hun Sen, who currently serves as sole prime minister, has changed his mind, however. He now feels that an international trial would be divisive and could plunge Cambodia back into civil war. He is wrong. The trial should proceed.