Various political, ethnic, and territorial disputes have been simmering in Central Asia since the collapse of the Soviet Union. A year before the USSR disintegrated there were riots in southern Kyrgyzstan over the Fergana Valley, when the Soviet authorities parcelled out land belonging to Uzbek collective farms to Kyrgyz citizens. The same ethnic divisions – amplified by political and social discontent – underpinned a major outbreak of violence in the southern Kyrgyz region of Osh in mid-2010 and again in the last half of 2012. Islamist violence remains a problem in Central Asia, even though the Islamic Movement of Uzbekistan (IMU), and its splinter group the Islamic Jihad Union, that began fighting in the 1990s for a separate sharia state has been much weakened. The authorities say that some of the 4,000 IMU militants who went to fight alongside the Taliban in Pakistan and Afghanistan have been filtering back to the Fergana Valley (now split between Kyrgyzstan, Tajikistan and Uzbekistan). With Islamists from Hizb-ut Tahrir also active, there are regular attacks on police and sporadic suicide bombings. In addition, Tajikistan nearly descended into civil war in August of 2012, with reports of Afghan militants aiding the opposition and slipping through the porous Afghan-Tajik border. Such instability is particularly worrying because the region, as a part of the Northern Distribution Network, is a major supply route for the NATO-led war in Afghanistan. It is also a major drugs-trafficking route where smugglers are arrested almost weekly with large amounts of heroin and other drugs.