Twenty years ago this week a military force took a break from their normal combat duties to dig extra trenches, procure lighting, find wire for ligatures and cloth for blindfolds. Theirs was not going to be a regular military operation: they were about to slaughter 8,000 unarmed Muslim men and boys.

Blindfolded, their hands tied behind their backs, most of the innocent were shot in the back with automatic weapons and deposited into mass graves. The lighting was brought in so the murder operation could continue through the night.

Rocket propelled grenades were also used at larger detention facilities. But in some cases, the evidence showed that the murderers may have opted to save their ammunition, and rather than bullets use a captive bolt pistol, which left their victims with bolt-sized holes in their skulls. The use of such a device left investigators, years later, trying to determine why some of the bodies they recovered from mass graves, had entry wounds, but no exit wounds.

Uncivilized. Ghastly. And it didn’t take place in war-torn Iraq or Syria; it all took place in modern Europe.

The slaughter, which commenced after the 11 July 1995 fall of a United Nations “safe area”, didn’t happen in a far-flung corner of the planet, but rather, just a few hours’ drive from where the world gathered to celebrate the Winter Olympics in Bosnia. And it occurred under the watchful eyes of the international community, including UN observers and a Dutch peacekeeping force.

The Srebrenica genocide has been coined “the worst atrocity in Europe since the Holocaust”.

And while there are those who may play politics, and try to avoid the nasty term “genocide”, as the shameful Russian veto at the UN Security Council recently showed, the International Criminal Tribunal for the former Yugoslavia – after hearing all the evidence, in trial after trial – has determined beyond a reasonable doubt that the generals and officers who stood in the dock in The Hague, charged for their role in the Srebrenica genocide, were guilty of war crimes and crimes against humanity, and in those cases where they found the necessary specific intent, “the crime of crimes” – genocide.

To be honest, I was not sure, at first, if the Tribunal would render a genocide verdict.

I had been here before. Years back I was a prosecuting attorney at The Hague, serving on the first Srebrenica genocide trial. Between our closing arguments and the final judgment, I decided to prepare myself for the ruling. I did this by looking for a precedent, spending a weekend at one of the places where evil took on a new name – that place was Auschwitz.

A notorious Nazi death camp in Poland, Auschwitz was part of the efficient slaughter operation now known as the Holocaust, which saw the murder of 6 million Jews, and millions of non-Jewish. It was from here that lawyer Raphael Lemkin created a word that did not yet exist: genocide.

The Nazis were methodical in their murder operations. But frankly, so were the Bosnian Serbs who led the slaughter at Srebrenica. Both were military operations, following a chain of command. Orders were issued, and followed; supplies requisitioned and disbursed. Indeed, having been commissioned as a US Army officer a few years before joining the Tribunal, I wondered how some of the suspects we interviewed, who were true professional soldiers, decided to take part in the genocide.

But they did. And that’s one of the many tragedies of genocide; that ordinary people, professional soldiers – truthfully, not all monsters, but some are – so wilfully perpetrate, aid or abet such terrible slaughters.

And perhaps that is one of the fears of people admitting to a word that means something so evil. It recognizes that as “civilized” as we may claim to be – even in cosmopolitan Europe – we can still be evil. Or put another way, we can lack enough empathy and compassion for our fellow man, to such an extent, that we act, or not act, resulting in genocide.

In the lead-up to the attack on Srebrenica, the Bosnian Serbs issued “Directive 7”, later produced as evidence at The Hague. A key passage reads: “By planned and well-thought out combat operations, create an unbearable situation of total insecurity with no hope of further survival or life for the inhabitants of Srebrenica…”

That Bosnian Serb General Ratko Mladic, now on trial in The Hague, and his henchmen, decided to take advantage of the chaos of the fall of the world’s first “safe area” and develop a plan, under the backdrop of Directive 7, to murder 8,000 innocents, was audacious. But it is also telling how people take advantage of opportunity, for good and bad, and use the language and position of authority, to carry out despicable acts.

This week, as we echo the all-too-familiar words, “We will never forget”, it might be worth remembering how language and position can be manipulated for evil – as ISIS is doing today – and pondering how often we chose to act, or not act – whether it be in Iraq, Syria or Libya – and the consequences for doing so.

As a Balkan ambassador recently told me: “There is a consequence for action and also one for inaction.” Let us hope that, 20 years after the international community stood idly by at Srebrenica, we become more thoughtful on how we choose to act, or not act. In doing so, we may just avoid another commemoration.

Author: Mark V. Vlasic, an adjunct professor of law and senior fellow at Georgetown University’s Institute for Law, Science & Global Security, served on the Slobodan Milosevic and Srebrenica genocide prosecution trial teams at the U.N. war crimes tribunal. A former White House Fellow/Special Assistant to the US Secretary of Defense and adviser to the President’s Special Envoy to Sudan, he leads the international practice at Madison Law & Strategy Group. He is a World Economic Forum Young Global Leader.

Image: A woman stands in front of the Memorial Center during a reburial ceremony of 136 newly identified victims in Potocari, near Srebrenica, Bosnia and Herzegovina REUTERS/Antonio Bronic