In recent years, reconstruction efforts have progressed and led to some political stability through a multiparty democracy under a constitutional monarchy although Sen's rule has been marred by human rights abuses and corruption. Cambodia's economy grew rapidly in the 2000s and 2010s, and it received considerable investment and infrastructure development support from China as part of its Belt and Road Initiative.Antigovernment protests in support of opposition party CNRP took place in Cambodia following the 2013 general election.A UN-backed war crimes tribunal, the Khmer Rouge Tribunal sought out to investigate crimes committed during the Democratic Kampuchea period and prosecute its leaders. However, Hun Sen has opposed extensive trials or investigations of former Khmer Rouge officials. In July 2010, Kang Kek Iew was the first Khmer Rouge member found guilty of war crimes and crimes against humanity in his role as the former commandant of the S21 extermination camp and he was sentenced to life in prison. In August 2014, the tribunal sentenced Khieu Samphan, the regime's 83-year-old former head of state, and Nuon Chea, its 88-year-old chief ideologue, to life in prison on war crimes charges for their role in the country's terror period in the 1970s.