TEL AVIV, Israel — One of Israel’s most controversial anti-terrorism tactics has been its policy of targeted killings of suspects believed to be planning attacks. Since the start of the second Palestinian intifada, or uprising, in the fall of 2000, dozens of members of the Palestinian groups such as Hamas, Al Aqsa Martyrs Brigades and Islamic Jihad have been assassinated by Israeli military and security forces. As American intelligence and armed forces continue to employ many Israeli counterterrorism and interrogation techniques, the question of whether targeted killings have become another arrow in the American quiver looms large.

In early 2006, citing American officials familiar with the U.S. program of drone-based assassinations, the Los Angeles Times reported that the program was expanding. It confirmed at least 19 incidents in which U.S. unmanned Predator drones successfully launched rockets against terrorist suspects abroad since the September 11, 2001, attacks. “In most cases, we need the approval of the host country to do them,” one former State Department counterterrorism official told the newspaper. “However, there are a few countries where the president has decided that we can whack someone without the approval or knowledge of the host government.”Several post-9/11 targeted killings of terrorist suspects have been publicly attributed to the U.S., though the CIA reiterated to the International Consortium of Investigative Journalists (ICIJ) its policy of not commenting on the subject. The first was the assassination of Ali Qaed Senyan al-Harthi, a senior al Qaeda operative linked to the 2000 terrorist bombing of the USS Cole in Yemen. His jeep (along with five other men in it) was blown up in Yemen in November 2002 by a missile fired from an unmanned CIA drone reportedly launched from Djibouti. In May 2005, reports surfaced that another CIA drone attack killed a Libyan al Qaeda suspect hiding out in Pakistan. Amnesty International, the international human rights group, worried that killing represented “an extrajudicial execution, in violation of international law.” In December that same year, Abu Hamza Rabia, another al Qaeda leader, was killed by a U.S. missile strike in Pakistan.

Anthony Dworkin, executive director of the Crimes of War Project, a nonprofit organization that raises awareness about the laws of war, said that no one knows the true extent to which the CIA or other American forces have engaged in targeted killings since the September 11 attacks. “I don’t know of anyone tracking targeted killings,” he said. “There is some ambiguity for what constitutes a targeted killing. The U.S. has been doing it in Afghanistan and Pakistan. … We don’t know exactly when targeted killings began.”

In 2003, then-Deputy Israeli Prime Minister Ehud Olmert (he is now the prime minister) revealed that Israel was considering a targeted killing of then-Palestinian leader Yasir Arafat. “In my eyes, from a moral point of view, this is no different than the eliminations of others who were involved in activating acts of terror,” The New York Times quoted Olmert as saying. Since his death in 2004, Palestinian officials and members of Arafat’s family have publicly speculated that Israel might have been involved in Arafat’s death, a charge Israel has denied.

In 2004, Hamas co-founder Ahmed Ismail Yassin was killed in Gaza by a missile fired from an Israeli helicopter. During the 2006 Lebanese war between Hezbollah and Israel, Israel tried to gather intelligence information pinpointing the whereabouts of Hassan Nasrallah, the secretary general of Hezbollah, and his top aides. In the early days of the war, Israeli aircraft attacked a bunker in southern Beirut, where it believed Hezbollah leaders were hiding, pounding it with what it described as 23 tons of bombs. (Hezbollah later said that none of its leaders were killed in the strike.)

The Israeli use of assassination as a national security method goes back decades. One important element of the tactic is that Israeli assassinations have been directed at foreigners, defined as “state enemies.” Targets over the years have included officers from Arab armies, German-Nazi scientists who worked for Arab military projects and Palestinian terrorists. Israeli intelligence agents, their foreign helpers and Israel’s military units executed the operations outside of Israel’s borders and in the occupied territories, but never inside Israel or against Israeli citizens.

“I flatly rejected requests and calls by cabinet ministers and my colleagues to assassinate Israeli citizens suspected of serious crimes against state security, regardless if they were Jewish or Arab,” the late Isser Harel, who headed Shabak (the Israeli equivalent of the FBI) from 1948 to 1952, said in a 2002 interview with ICIJ. “I also insisted that they would be brought to court and charged.”

“The GSS [Shabak] under my directorship, whose jurisdiction was within Israeli borders, neither killed nor tortured Israeli citizens — neither Israeli Jews nor Israeli Arabs,” Amos Manor, who served as the head of Shabak from 1953 to 1963, echoed in another 2002 interview with ICIJ. “Even if an Israeli citizen was suspected of treason, we would do our utmost to capture, interrogate and eventually charge him and put him on trial. I was very sensitive not to break the law. The only unlawful operations we conducted at the time were penetrations and breaking into houses to collect information about the targets.”

The first known targeted killing occurred in 1956, when an Israeli agent gave a rigged parcel to Col. Mustafa Hafez, the director of Egyptian military intelligence in Gaza, which was then under Egyptian control. When Hafez opened the package, it exploded in his face, mortally wounding him.

In the early 1960s, the Mossad, Israel’s equivalent of the CIA, sent letter bombs to German scientists who it believed were working on chemical, biological and nuclear weapons for Egypt. The operation backfired; not only were the hits unsuccessful, but they threatened to harm Israel’s diplomatic relations with West Germany. As a result, Harel was forced to resign as Mossad chief, a post he held after heading Shabak.

Nevertheless, Israeli intelligence continued to use targeted killings. About two dozen people — including both suspected Arab and Palestinian terrorists and agents suspected of double-crossing Israel — were assassinated in the 1960s and early 1970s, according to ICIJ interviews with members of Mossad and Shabak who spoke on the condition of anonymity. In some cases, the agents said, the double agents were tricked by their handlers into handling booby-trapped explosives, creating the illusion that they were killed in bomb-making accidents.

After the world was shocked by the killing of 11 Israeli athletes by Palestinian terrorists at the 1972 Munich Olympics, Israeli intelligence sent secret hit teams to Europe disguised as tourists and businessmen.

“Until Munich, the Israeli policy was based on the assumption that European governments would take responsibility and would not allow terrorism on their soil,” then-Mossad chief Zvi Zamir told ICIJ. “But when we in the Mossad realized that the Europeans had no intentions of dealing and stopping terrorism we persuaded Premier [Golda] Meir to allow us to act, even though it was unlawful from the point of international law” to carry out assassinations on foreign territory.

Zamir insisted that the motive was not revenge — as depicted in the Steven Spielberg film “Munich” — but to disrupt a Palestinian terror network that might strike again.

“We targeted those who could pose a threat in the future by launching more terrorism,” Zamir said. “Those who say, like in the movie, that we were motivated by revenge talk nonsense. Revenge was not in my vocabulary.” Zamir said that Meir and several other top Israeli government officials approved the targets, based on a list compiled by Mossad.

The operation killed nine Palestinians, but like the 1960s plot against the German scientists, it soon backfired in spectacular fashion. In 1974, Mossad killed a man in Lillehammer, Norway, it believed to be Ali Hassan Salameh, a senior officer with the Palestinian Liberation Organization’s special operations and the reputed mastermind of the Munich attack. Instead, he turned out to be Ahmad Boushiki, an innocent waiter married to a Norwegian woman. Five Israeli agents were convicted by a Norwegian court and served short jail sentences related to their involvement in Boushiki’s death.

The incident embarrassed the Israeli government. It also caused some within Mossad to question whether the agency was straying too far from its intelligence-gathering mission by engaging in assassinations, former Mossad officials told ICIJ.

Nevertheless, the targeted killings continued. In 1977, Mossad used a Palestinian collaborator to provide Wadia Haddad, an operative of the Popular Front for the Liberation of Palestine, with poisoned chocolates. He died the following year from what appeared to be leukemia. A year later, an Israeli intelligence agent in Beirut triggered a car bomb that finally killed Salameh, the intended target of the Lillehammer operation.

In 1992, Israeli helicopters flew to Lebanon and used missiles to assassinate Seyyed Abbas Musavi, the Hezbollah secretary general. In 1995, Mossad agents in Malta shot to death Dr. Fathi Shkaki, leader of the Palestinian terrorist group Islamic Jihad, which was responsible for the first suicide attacks on Israeli buses.

In 1997, another Mossad poison plot in Jordan nearly killed Hamas leader Khaled Mashaal. And once again, a targeted killing attempt backfired. The plot was discovered by the Jordanian government, which then compelled the Israelis to provide Mashaal with an antidote. The incident damaged relations between Jordan and Israel, and then-Premier Benjamin Netanyahu had to agree to cooperate with a first-ever parliamentary inquiry into the secret Israeli policy of targeted killings.

The following year, the investigation’s scathing conclusion was that Israeli assassins operated without clear, consistent guidelines and as a result, targeted killings “carry heavy and damaging weight.”

Over the years, Israel’s targeted killings policy has drawn widespread international criticism. More recently, Israeli peace groups petitioned the Israeli Supreme Court to rule that targeted killings were illegal.

One reason targeted killing should be banned, critics say, is that innocent civilians often are killed in the attacks. In a 2006 letter to Israeli Prime Minister Olmert and Minister of Defense Amir Peretz, the Israeli human rights group B’Tselem contended that since 2000, assassination attempts against suspected Palestinian terrorists have killed 123 non-targeted civilians. “When an assassination is carried out through the firing of missiles from the air on a car that is traveling during the day in a crowded residential area,” the group wrote, “the chance that civilians will be harmed is almost certain.”