What country is/was Norodom Sihamoni a citizen of?

Cambodia is the country of citizenship for Norodom Sihamoni.
Cambodia (; also Kampuchea, officially the Kingdom of Cambodia, is a country in the southern Indochinese Peninsula in Southeast Asia, spanning an area of 181,035 square kilometres, bordered by Thailand to the northwest, Laos to the north, Vietnam to the east, and the Gulf of Thailand to the southwest.