Mass demonstrations over the future of Ukraine took place in 2013 and 2014. In March 2014, Russia annexed the Crimean Peninsula and from the spring of 2014 pro-Russian separatists engaged Government forces in Eastern Ukraine, taking over several large towns. In June 2014 Russia invited the Organization for Security and Cooperation in Europe (OSCE) to monitor border crossings between Russia and Ukraine: however, OSCE monitors were subsequently abducted by pro-Russian rebels and held for several weeks. Interrupted international monitoring and the absence of reliable statistics have made it difficult to collect credible data on the activities of the Ukrainian armed forces and pro-Russian rebel groups. Thousands of refugees have fled from contested or occupied towns and villages and it is believed that thousands have gone missing as a result of refugee flight, fighting, reprisals and abductions. A report by Amnesty International found evidence of torture and forced disappearances carried out by both sides. In May 2014, Human Rights Watch issued a report documenting widespread human rights violations in Eastern Ukraine. In July, the Ukrainian authorities excavated a mass grave in the town of Sloviansk In July 2014 a Malaysian airliner departing from Amsterdam Schiphol Airport was shot down over territory controlled by pro-Russian separatists. All 298 passengers and crew were killed and the international effort to collect and identify the bodies and arrange for burial were obstructed by armed men on the ground. At the invitation of the Ukrainian Government and under the terms of its standing agreement with INTERPOL to provide assistance in case of disasters, ICMP deployed with INTERPOL at the crash site to assist in recovering victims’ remains that were subsequently transported to The Netherlands.