The 2008 assassination of a Hezbollah leader entrenched in some of the Islamist militant group’s most dramatic terrorist attacks was planned and executed under a joint effort of Israel and the United States. Among the incursions that involved Hezbollah’s international operations chief Imad Mughniyeh were those against the Israeli Embassy in Argentina and the U.S. Embassy in Beirut.

Although the U.S. has not admitted its involvement in the killing, five anonymous former U.S. officials have now confirmed the involvement of the U.S. Central Intelligence Agency (CIA) to The Washington Post. The mission is considered one of highest-risk undercover actions by the U.S. in recent memory.

It was after dinner in February, 2008 that Hezbollah leader Mughniyeh was killed by a car bomb in Syria’s capital, Damascus. Before the explosion, spotters from the CIA watched his movements while agents of Israel’s intelligence agency, Mossad, triggered the bomb remotely from Tel Aviv. Under this design, one of the officials said that, if it deemed it necessary, the U.S. could call off the assassination but it could not implement the actual explosion.

According to the newspaper, Israel approached the CIA about execution of the cooperative venture to Mughniyeh. Both agencies, CIA and Mossad, followed Mughniyeh’s movements in Damascus for months and, with their acquired information, together determined where and how the bomb should be installed.

Mughniyeh was connected to the deaths of hundreds of Americans, including in the 1983 bombing in Beirut that killed 63 people. It was on this basis that the Bush administration labeled the killing of Mughniyeh as national self-defense because he was actively involved in plots against the U.S. An official who served the U.S. in Baghdad said that, at the time, “There was an open license” to “finish Mughniyeh and anybody affiliated with him.”

Monitoring of Mughniyeh’s movements in Syria showed that he took occasional evening walks by himself. Suggested by Mossad, such a walk was reportedly a best scenario to accommodate the CIA’s desired to ensure no other people (collateral damage) were injured by the bomb’s blast.

The U.S. / CIA has declined to comment about the Hezbollah leader’s assassination and a spokesman for Benjamin Netanyahu, the prime minister of Israel, said there was “nothing to add at this time.”