“If the bombing starts again we’ve been told we will die.” The chilling words of the unarmed Canadian officer radioed to United Nations headquarters in Sarajevo, just hours after NATO jets had struck a Bosnian Serb ammunition dump to punish noncompliance with UN resolutions.

Now the officer and his colleagues were held by the Bosnian Serbs as human shields. The threat to their lives was obvious, though whether they would die at the hands of their captors or as casualties of bombing was unclear. Television pictures showed them chained to the door of a munitions facility and being forced to drive their car to and fro across the air-raid rubble to prevent the planes returning. A forlorn Polish officer was handcuffed outside a radar site while two masked Serb soldiers stood by, shotguns balanced on their hips. The black hoods, which made the guards look like executioners, were to conceal their identities.

Those two Serbs were taking warranted precautions. Indictments for war crimes had already been handed down by the Hague Tribunal, and the Bosnian Serbs knew their actions would be closely scrutinized. Since 1949, the taking of hostages has been forbidden by the four Geneva Conventions. Using prisoners of war or detainees as human shields has been outlawed either specifically or implicitly by clauses that forbid a party from harming those “not actively taking part in hostilities” in its control.

Common Article 3 of the conventions bans the taking of hostages in internal conflicts while the Fourth Convention forbids civilians being taken hostage during times of war. Ignoring these prohibitions during an international conflict is a grave breach of humanitarian law, leaving those responsible liable to international pursuit and prosecution. The conventions also decree that both prisoners of war and civilians should not be “used to render certain points or areas immune from military operations.” Civilians get further protection from the 1977 Additional Protocol to the Geneva Conventions dealing with internal conflicts. It, too, bans hostage taking.

The practice of taking hostages in war has a long pedigree. In the past, it was used to secure the obedience of an occupied people or adherence to the terms of a treaty. The practice was specifically outlawed in 1949 because of the finding at the Nuremberg Trials that existing laws appeared to permit reprisal executions. Under certain conditions an army is still allowed to take reprisals for an illegal act by an adversary, but cannot use “excessive” force or execute prisoners of war or civilians.

The International Committee of the Red Cross (ICRC) defines hostages as “persons who find themselves, willingly or unwillingly, in the power of the enemy and who answer with their freedom or their life for compliance with the orders of the latter (the enemy) and for upholding the security of its armed forces.”

Disputes about the nature of modern conflicts make it difficult to judge if and how the protections of the Geneva Conventions apply. Should you be hijacked on an international flight, your abductors would not be contravening the Geneva Conventions, which deal with hostages taken by “an authority,” but the 1979 International Convention Against the Taking of Hostages, which explicitly outlaws such cross-border criminality.

“Hostages” was the description the UN gave to the four hundred peacekeepers the Bosnian Serbs rounded up from depots and garrisons at the end of May 1995. The ICRC, however, disagreed. It argued that since the UN had ordered air strikes it had become involved in the Bosnian conflict and its personnel were therefore prisoners of war. The ICRC did make plain its horror that once they were forced to serve as human shields they were being used as hostages and not treated as prisoners of war. The Hague Tribunal subsequently indicted Bosnian Serb leaders Radovan Karadzic and Ratko Mladic for the hostage-taking campaign and for using UN personnel as human shields.

At the time, unfortunately but unsurprisingly, the Bosnian Serb tactic worked. “I was a kind of insurance policy against NATO threatening to bomb again,” said Capt. José Mendez after his release. The Spanish officer spent ten days sitting in the middle of a runway at the main Bosnian Serb air base hoping that NATO would not call the Serb bluff. It did not. The next NATO bombing campaign, which led to the Dayton peace agreement, took place when UN soldiers were no longer vulnerable to capture.

(See reprisal killings.)