The assassination of Imad Mugniyah, the Hezbollah terrorist, in Damascus last week was a warning that even the most elusive prey can be hunted down -- given skill, determination and patience on the part of the hunter. The blast that dispatched Mr. Mugniyah, a top target for Israeli and American intelligence for most of three decades, was heard loud and clear by Khaled Mashal, the exiled political chief of Palestinian Hamas, who at the time was meeting with Syrian intelligence officers only a few hundred yards away.
In 1997, Mr. Mashal escaped death at the hands of the Mossad, the Israeli spy agency, when a poisoning attempt in Amman, Jordan, went disastrously wrong. This was one in a series of botched operations, culminating in the failures of the 2006 Lebanon war, that nearly wrecked the Mossad's once-lofty reputation.
Although Israel has denied carrying it out, the Mugniyah hit was exactly the kind of thing needed to restore that reputation. Pinpointing the location of this evasive quarry, placing an explosive charge in his S.U.V. precise enough to kill him and no one else ("Pity about that new Pajero," chuckled one intelligence official in Tel Aviv), and operating in the heart of an Arab capital saturated with secret police -- this is the stuff that gave the Mossad its name.
Indeed, Israeli and American intelligence agencies have recently racked up a number of successes in their clandestine war against Iran and the terrorist movements it backs. It may be no coincidence that the Damascus operation followed the apparent defection to the United States last year of an Iranian general, Ali Reza Asgari, who in the 1980s had helped Mr. Mugniyah establish Hezbollah as a military force in Lebanon.
But however much backslapping and Champagne-cork popping may be going on in Tel Aviv and Langley, Va., the questions remains: Was it worth the effort and resources and the mortal risk to the agents involved? Few would deny that Mr. Mugniyah, who had the blood of many hundreds of Americans and Israelis, not to mention Frenchmen, Germans and Britons, on his hands, deserved the violent death that befell him, or that eliminating this top-flight mass murderer might prevent more death. But this act of combined vengeance, punishment and pre-emption might extract a far greater cost in the future.
At Mr. Mugniyah's funeral on Thursday, Hezbollah's leader, Sheik Hassan Nasrallah, threatened to retaliate against Israel, saying, "Let it be an open war anywhere." The Israeli Counterterrorism Bureau warned Israelis traveling outside the country to avoid Arab or Muslim countries, remain on "high alert" and beware of kidnapping.
There are precedents. It was on Feb. 16, 1992, that Ehud Barak, then chief of staff of the Israeli military and now minister of defense, gave the order for two combat helicopters hovering over south Lebanon to rocket a convoy in which the Hezbollah leader, Sheik Abbas Musawi, was traveling. Sheik Musawi, his wife and his 6-year-old son were killed. The response was not long in coming: for five days, Katyusha rockets rained down on northern Israel. A 5-year-old girl was killed.
This was only the beginning. Watching television coverage of Sheik Musawi's assassination at their home in Turkey had been Ehud Sadan, chief of security at the Israeli embassy in Ankara, and his wife. "I hope this doesn't spark a war of assassinations," Mrs. Sadan said. Her husband reassured her that nothing would happen. On March 7, he was blown up by a bomb planted under his car. The authorities arrested several members of Turkish Hezbollah, acting under orders from Mr. Mugniyah.
Ten days after that, Mr. Mugniyah's men blew up the Israeli Embassy in Buenos Aires, killing 29 people and wounding more than 220. Two years later, in July of 1994, a suicide bomber struck at the offices of a Jewish community organization in Buenos Aires, killing 85. A joint investigation by Mossad and the Central Intelligence Agency uncovered clear evidence of Mr. Mugniyah's involvement in all three bombings. The telephone monitors of the United States National Security Agency turned up "not a smoking gun, but a blazing cannon," in the words of a Mossad official. A senior Hezbollah operative, Talal Hamiyah, was taped rejoicing with Mr. Mugniyah over "our project in Argentina" and mocking Israeli security services for not preventing it.
Ever since, the Israelis have been very cautious about assassinating Hezbollah leaders. Two weeks before Israel withdrew from Lebanon in May 2000, military intelligence had Mr. Mugniyah in its sights. Mr. Barak, then prime minister, ruled out a hit, for what he claims were operational reasons, but he surely had the aftermath of the Musawi assassination in mind.
Today, whether Mr. Barak has unlearned his lesson or not, Hezbollah has no doubt that it was Israel who eliminated its top terrorist, and once more it is bent on vengeance. As Hezbollah draws no fine distinctions between the United States and Israel, both nations, along with Jews around the world, might well have to pay the price for the loss of the man whose mystical aura was as important as his operational prowess.
In the immediate aftermath, Hezbollah has chosen not to respond with volleys of rockets aimed at Galilee, as many Israelis feared. But an inkling of how the group might respond can be found in the July 2007 statements of Michael McConnell, America's director of national intelligence, expressing grave apprehension about Hezbollah sleeper cells in the United States that could go into action should the Americans cross the organization's "red line."
This line has now been crossed. Only the severest of countermeasures by the intelligence services of Israel and the United States will prevent last week's assassination, justified as it was, from costing a vastly disproportionate price in blood.
Ronen Bergman, a correspondent for Yediot Aharonot, an Israeli daily, is the author of the forthcoming book "The Secret War With Iran."