LONDON — As Europe marks the 20th anniversary of the massacre of about 8,000 Muslim men and boys in the Bosnian town of Srebrenica, reconciliation has been halting in a region where memories and wounds, personal and political, run deep.

Bosnian Serb nationalist leaders have sought to play down the events at Srebrenica, and leading Bosnian Muslim officials express frustration that the 1995 Dayton accord, which ended the war, granted the Bosnian Serbs autonomy in their territory.

There is division even over what to call the mass killing. Although two international tribunals based at The Hague have ruled that it constituted genocide, Russia on Wednesday vetoed a draft United Nations Security Council resolution that condemned the massacre as a “crime of genocide,” with its ambassador to the United Nations, Vitaly I. Churkin, calling the language of the measure “confrontational” and “politically motivated.”

And in the killing fields in and around Srebrenica, the remains of victims — arms, legs and heads hidden by Bosnian Serb forces — are still being discovered, causing more pain for their loved ones.

The atrocity was the worst in Europe since World War II, and the exhumations are a vivid reminder that while the brutal violence of the Islamic State and Boko Haram has dominated the headlines recently, a mass killing took place on European soil for three days starting July 11, 1995, while the world looked the other way.