20th Anniversary of Srebrenica Massacre, Potocari, Bosnia and Herzegovina -- July 11, 2015

A woman cries as the remains of her son are buried at the Potocari memorial complex near Srebrenica, 150 kilometers northeast of Sarajevo, Bosnia and Herzegovina, July 11, 2015.

A Bosnian man walks among graves during a funeral ceremony for the 136 victims at the Potocari memorial complex near Srebrenica, 150 kilometers (94 miles) northeast of Sarajevo, Bosnia and Herzegovina, July 11, 2015.

People pray during a funeral service at the Potocari memorial complex near Srebrenica, 150 kilometers northeast of Sarajevo, Bosnia and Herzegovina, July 11, 2015.

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, July 11, 2015.

Aleksandar Vucic, Serbia's prime minister, center, is seen during a scuffle at the Potocari memorial complex near Srebrenica, 150 kilometers northeast of Sarajevo, Bosnia and Herzegovina, July 11, 2015.

Former United States President Bill Clinton delivers a speech during a ceremony marking the 20th anniversary of the Srebrenica massacre in Potocari, near Srebrenica, Bosnia and Herzegovina, July 11, 2015.

Former U.S. President Bill Clinton tours the former battery factory at Potocari memorial complex marking 20th anniversary of the Srebrenica massacre of Potocari, 150 kilometers northeast of Sarajevo, July 11, 2015.