"The guerrillas blew up the hospital."

I still vividly remember the scorching hot day in November 1989 when I heard those words and instantly recognized that there might be a story behind them. I was working as Central America correspondent for Newsweek. El Salvador was in the middle of a ferocious nationwide offensive by a Marxist guerrilla group known as the Farabundo Marti National Liberation Front (FMLN). The FMLN had surprised the Salvadoran Army with large-scale coordinated attacks on the capital, San Salvador, and all the major provincial towns across the tiny, Massachusetts-size country. One of the towns they hit was Zacatecoluca, a provincial capital near the country's international airport. Amid the ensuing chaos, both sides charged each other with horrific human rights violations. It was in that atmosphere that I heard the first report of a guerrilla assault on the hospital in Zacatecoluca.

Hospitals, of course, enjoy a special protected status under international humanitarian law. It is a war crime deliberately to attack a hospital or other medical unit, whether civilian or military. It is also unlawful to use a hospital in direct support of a military operation—to convert one wing of the hospital into an ammo dump, for example. (Indeed, hospitals that are misused in this manner lose their legal protection.) Medical personnel in general may not be attacked; but at the same time it is unlawful to use medical facilities, or related equipment such as ambulances, as camouflage or protection for military personnel, or as a shield for military forces.

International humanitarian law is not, however, completely inflexible in how it evaluates collateral damage to hospitals that may result from attacks on legitimate military targets nearby. The rule of thumb is that if the damage to the hospital is not excessive in view of the direct and concrete military advantages to be gained from attacking the nearby target, then the damage may be considered lawful.

To go back to that hot day in El Salvador nine years ago. I clambered into my beat-up Mitsubishi Montero Jeep and took off down the road for Zacatecoluca. I will never forget the shock I felt when, without warning, a huge explosion erupted from what seemed like only two inches from my right ear. Temporarily deafened, I recovered my other senses enough to realize that an army artillery piece had just been fired from about twenty-five yards away; the Salvadoran military was pouring shells into the hills around Zacatecoluca, in a desultory attempt to deal with the retreating guerrillas.

When I reached the town, I made immediately for the large, modern public hospital not far from the main square. Once inside, I did indeed find that the pediatric ward had been blown to smithereens. Windows were broken, the elevator destroyed, bits of bedding lay strewn about on the floor. And the hospital personnel confirmed to us that the damage had been caused when a guerrilla unit detonated a large bomb in the ward.

End of story? Not quite. The destruction was heavy, but not entirely wanton. There had been heavy fighting that day between the army and the guerrillas. Neither side occupied the hospital or attempted to do so, but as the fighting raged among the narrow cobblestoned streets of the town, a few Salvadoran Army soldiers had become separated from their unit and attempted to flee onto the roof of the hospital. The FMLN forces cornered the government soldiers, and, in an attempt to flush them out, decided to detonate an explosive charge in the pediatric ward, the spot nearest to the soldiers' rooftop hideout.

Hence, two crucial legal questions arise: First, were the soldiers a legitimate target for the FMLN? Almost certainly yes. (It could even be argued that the hospital lost its protected status because the soldiers chose to hide themselves there, but their flight onto the hospital roof seemed less calculated than a decision made amid the heat and panic of battle, with no cooperation from the hospital staff, and it would seem perverse to make the hospital pay for that.)

Second, were the FMLN troops within their rights to use an explosive to attack the soldiers, knowing that to detonate it would cause substantial damage to the wing of the hospital where civilian children were treated? I think that in this instance, the answer is also yes—especially in view of the fact that hospital personnel told us that the guerrillas gave them ample warning and permitted them to evacuate all the patients and medical personnel before they set off their bomb.

But it is a qualified yes. The answer, under international law, would ultimately hinge on the question of whether killing or capturing a handful of already fleeing enemy troops really warranted the eminently foreseeable damage to a hospital facility. And that damage was extensive; not total destruction of the entire building, to be sure, but serious enough to force dozens of sick and injured people into a makeshift outdoor clinic. It might reasonably be argued that this level of damage was unwarranted, notwithstanding the FMLN's laudable effort to evacuate the building first. In fact, the FMLN never did capture or kill the soldiers. If humanitarian law was violated, the FMLN theoretically might be required to pay reparations for the damage caused. But there was no evidence of willfulness in the legal sense required to constitute individually culpable war crimes.

So I went back to San Salvador and incorporated the Zacatecoluca hospital incident into that week's article. It was true, as I initially heard, that the guerrillas had blown up the hospital. But a close investigation of all the factors that led them to take that action, and of the manner in which they took it, showed that, tragic as it was, the assault may well have fallen into the category of a questionable but lawful military action, rather than that of a major violation of human rights or an individually culpable war crime.