U.S. President Barack Obama has taken George W. Bush's war on terror to a new level, approving, as journalist David Rohde recently put it in Foreign Policy, "more targeted killings than any modern president" through drone strikes against suspected militants from Pakistan to Somalia to Yemen. The idea of decapitating the enemy's leadership stretches at least as far back as the fourth century B.C., when Emperor Chandragupta Maurya assassinated two Greek governors as part of his conquest of India, though the tactic has become more common over the last century. But what makes targeted killing different from assassination, which the United States banned decades ago? And how has the legal justification evolved for a practice that has become so prominent that the president now personally decides which enemies of the state should live or die?
Following a half-century of efforts to develop international rules for warfare, a peace conference at The Hague produces a treaty prohibiting "belligerents" in an "armed conflict" from killing "treacherously individuals belonging to the hostile nation or army." But key terms such as "treacherously" and "armed conflict" aren't defined in The Hague Convention or its successor agreement, the 1949 Geneva Conventions. To this day, these ambiguities in the law of war cloud distinctions between peacetime and wartime, and between illegal assassinations and legal efforts to kill specific individuals.
The Austro-Hungarian empire accuses the Serbian government of playing a role in the assassination of its heir to the throne, Archduke Franz Ferdinand, by Gavrilo Princip, a Bosnian Serb nationalist. The standoff helps spark World War I.
In the final months of World War II, the British plot to assassinate Adolf Hitler. Schemes include sending a sniper to take out the Führer during his morning walk and poisoning his tea. British officials debate whether killing Hitler will help them win the war -- not whether assassinating him is legal -- but the plans are never implemented.
The Cold War ushers in a flurry of state-sponsored extrajudicial political assassinations outside the bounds of war, including the killing of recently ousted Congolese Prime Minister Patrice Lumumba, who appeared to be drifting into the Soviet orbit, by domestic rivals acting with Belgian assistance.
The CIA spearheads the Phoenix program, a covert counterinsurgency seeking to "neutralize" Viet Cong operatives in South Vietnam. President Richard Nixon embraces the effort, which kills more than 26,000 Viet Cong by the end of 1972. "We've got to have more of this," he reportedly tells his budget director in 1969. "Assassinations. Killings. That's what [the Vietnamese communists are] doing."
Israeli Mossad agents begin covertly hunting down and killing Palestinian militants abroad in retaliation for their suspected role in the murder of 11 Israeli athletes and coaches at the Munich Olympics. The operation causes an uproar in 1973 when Israeli agents mistake a Moroccan waiter in Norway for the mastermind of the Munich attack and gun him down.
After Seymour Hersh's famous New York Times exposé on the CIA's illegal activities, the Senate's Church Committee uncovers assassination attempts against foreign leaders such as Cuba's Fidel Castro. In response, President Gerald Ford issues an executive order banning "political assassination" by the U.S. government -- an order future presidents reaffirm. But the assassination ban applies to peacetime, not wartime. "[S]hort of war," the committee concludes, assassination "should be rejected as a tool of foreign policy."
The human rights group Americas Watch begins using the phrase "targeted killings" synonymously with "assassination" to distinguish the killing of specific people outside combat by military forces and death squads in El Salvador from the indiscriminate killings they also perpetrated.
In response to the bombings of U.S. embassies in Kenya and Tanzania, President Bill Clinton launches cruise missiles at Osama bin Laden's suspected training camp in Afghanistan and authorizes covert operations to capture the al Qaeda leader if possible and kill him if necessary. Administration officials reason that the assassination ban does not apply to a military target like bin Laden, who planned the embassy attacks, and that the United States would be exercising pre-emptive self-defense if it killed him.
Israel, which has been targeting terrorist leaders since the 1970s, conducts its first publicly acknowledged assassination, dispatching a helicopter gunship to kill Palestinian militia leader Hussein Obaiyat in Bethlehem. International media begin referring to Israel's "targeted killing" policy against Palestinian militants, and George W. Bush's administration comes out in opposition to the practice.
Days after the 9/11 terrorist attacks, the U.S. Congress passes the Authorization for Use of Military Force, enabling the government to kill members of al Qaeda and its affiliates as part of America's first war against a nonstate actor. The Bush administration's new national security strategy builds on the Clinton team's rationale for targeting bin Laden. "To forestall or prevent … hostile acts by our adversaries," the document explains, "the United States will, if necessary, act preemptively."