Like it or not, we have entered a new era in the war against terrorism. The CIA last week used an unmanned plane to track a carload of people judged to be terrorists across the vast “Empty Quarter” of northwestern Yemen. The plane wiped them out with a single missile. All that was left was burned-out wreckage including traces of explosives and remnants of communications equipment. There must have been some charred body parts, but unnamed officials who disclosed the operation did not mention them.

The plane was an armed Predator, flown by the CIA and used for the first time outside Afghanistan. Just how the car was first spotted and whether President Bush personally gave the order to fire the missile are matters of conjecture. The White House and the CIA are not saying much. Presumably, Yemeni intelligence was involved, but U.S. Special Forces on the ground may have taken part. Mr. Bush is said to have delegated authority for specific strikes to senior officials.

This small unmanned plane flies at heights of 10,000 to 15,000 feet, probably unseen and unheard from the ground.

It uses direct satellite links and is fitted with an infrared camera and all-weather radar to penetrate any cloud or dust cover. Some say that its 900-millimeter zoom lens can read a license plate and compare faces with data-bank pictures of terrorists. In this case, officials say the victims were all al-Qaida operatives headed by Qaed Salim Sunan al-Harethi, also known as Abu Ali, who is believed to have taken part in the attack on the USS Cole in Aden harbor two years ago.

The armed CIA Predator was used once before in an attempt to kill the Taliban leader, Mullah Muhammad Omar. He was spotted and within range, but the attack was aborted. Varying explanations were that the CIA did not yet have shoot-to-kill authorization and that others in a crowded house might have been killed.

An obvious downside of this new style of warfare is that it could earn the United States a reputation for designating itself as judge, jury and executioner. Sweden’s foreign minister, Anna Lindh, called the operation “a summary execution that violates human rights.” She said, “Even terrorists must be treated according to international law. Otherwise, any country can start executing those whom they consider terrorists.”

So this new form of surgical strikes should be used sparingly and only when identification is certain. Even then, the backlash against this new warfare may outweigh the gains. Still, it may be one effective way to fight back against a secretive, stateless, deadly conspiracy with cells around the world waiting to commit further attacks on Americans.