Again and again, they came. Truckloads of men and boys, blindfolded, their arms tied, were lined up by the gunmen in fields and forests, sometimes told to pray, then shot dead with Kalashnikovs. The killings, systematic and methodical, lasted days, from 11-14 July 1995, on the outskirts of a small eastern Bosnian Muslim mining town that UN peacekeepers were meant to protect as a “safe haven” – but didn’t.

The only survivors were those who hid under dead bodies and crept away, once night had fallen. Later the killers returned to dig up bodies from the mass graves and scatter them in an effort to hide their crime. To this day, forensic experts are still identifying human remains, pieces of limbs and skulls, and Bosnian families struggle to come to terms with their loss.

It was the worst crime on European soil since the second world war. Twenty years ago, about 8,000 Muslim men and boys from the town of Srebrenica were massacred by Serbian forces under the command of General Ratko Mladic, the then Bosnian Serbian military leader, whose trial for genocide opened a little over a year ago at the international criminal court in The Hague.

As the 20th anniversary of this carnage approaches, you might have thought that there would only be dignified remembrance, international consensus to honour the dead, and more efforts towards stabilising the Balkans. Instead, there have been power plays and a major diplomatic hiccup at the UN, with Russia vetoing a western-sponsored resolution calling the Srebrenica massacre an act of genocide.

This is an episode that arguably says as much about how hard it has become for Europe to defend some of its core principles and values as the Greek quagmire does. And the consequences could be just as far-reaching.

As I read the comments of Russia’s representative at the UN, Vitaly Churkin, defending his country’s veto on the Srebrenica resolution, I thought of George Orwell, who once wrote: “Political language is designed to make lies sound truthful and murder respectable, and to give the appearance of solidity to pure wind.”

Chechnya, the key military campaign in Putin’s career explains why Srebrenica is a symbol Russian diplomacy must counter

It’s not that Churkin denied that an atrocity had been committed. Rather, he described the resolution project as politically motivated and anti-Serbian. But what bothered Russia most was the use of the G-word.

Of course, from the Armenian tragedy to Rwanda and Darfur, it is nothing new that debate over the very use of the term genocide has been politically charged. The word, which combines geno (race or tribe in ancient Greek) with cide (to kill in Latin), was coined by the Polish-Jewish jurist Raphael Lemkin, and adopted by the UN in 1948. Genocide is defined as killings that have the “intent” to exterminate part, or the totality, of an ethnic, national or religious group. Since Soviet times Russian leaders have been reluctant to use such vocabulary. Some say that it is linked to Russian antisemitism, others point to Moscow’s old insistence on preserving Soviet deaths in the second world war as an overarching, unchallenged narrative.

But Russia’s latest decision to divide the security council over Srebrenica has more geopolitical than theoretical motivations. It relates to Russia’s currently revived ambitions in the Balkans, to its readiness to offer an alternative to western-promoted endeavours and norms, and to its quest for opportunities to play on European divisions. Old Russian overtures to Serbia, a candidate for EU accession but whose successive governments have rejected the term genocide for Srebrenica, are at the heart of this.

Russia’s veto comes across as an act of defiance against UN-sponsored international justice, which ruled that the Srebrenica massacre was an act of genocide. It also flies in the face of all the arguments the west made in the 1990s for liberal intervention. Srebrenica was a major trigger for the Nato operation that put an end to the Bosnian war and the sinister dreams of a “Greater Serbia” that had fuelled it.

It matters because these were the foundations of the Dayton peace agreement, and later of the EU’s process to bring in the Balkans – all very much unfinished and uncertain business to this day. Manipulating the very memory of Srebrenica unleashes old hatreds that Russia can easily play on to get a foot in the door and increase its influence.

But there is, I would argue, another more personal and political factor. Slobodan Milosevic, just as Vladimir Putin has done in Ukraine and before that in the Caucasus, blew the flames of militaristic patriotism to consolidate his hold on power. Even if no international tribunal has ever been created to rule on whether genocide was committed in Chechnya (approximately 50,000 dead between 1999 and 2003), this key military campaign in Putin’s political career explains why Srebrenica is a symbol that Russian diplomacy must counter.

Some will argue that Russia’s latest veto should be seen as just another snub to the west. But the rewriting of the history of the Bosnian war and the unravelling of the mechanisms that the west tried to put in place to prevent more violence are something that Europeans would do well not to minimise. If only because of those unarmed 8,000 men and boys who were killed just because of who they were: Bosnian and Muslim.