The politics of Cambodia are defined within the framework of a constitutional monarchy, in which the King serves as the head of state, and the prime minister is the head of government. The collapse of communism set in motion events that led to the withdrawal of the Vietnamese armed forces, which had established their presence in the country since the fall of the Khmer Rouge. The 1993 constitution, which is currently in force, was promulgated as a result of the 1991 Paris Peace Agreements, followed by elections organized under the aegis of the United Nations Transitional Authority in Cambodia. The constitution proclaims a liberal, multiparty democracy in which powers are devolved to the executive, the judiciary and the legislature. However, there is no effective opposition to the Prime Minister Hun Sen, who has been in power since 1984. His Cambodian People's Party won all 125 seats in the National Assembly in 2018 after the banning of opposition party CNRP. Furthermore, the governing charter declares Cambodia to be an "independent, sovereign, peaceful, permanently neutral and non-aligned State."