Cambodian King Norodom Sihamoni left Phnom Penh for Vietnamese capital Hanoi on Wednesday morning, as he embarked on a three-day “friendship building” official visit to the country, which is due to wrap-up on Friday.

The King, 65, was seen off at Phnom Penh International Airport by Prime Minister Hun Sen, Senate president Say Chhum, National Assembly president Heng Samrin, Interior Minister Sar Kheng, National Defence Minister Tea Banh, along with other government leaders, royal family members and Vietnam’s Ambassador to Cambodia, Vu Quang Minh.

The King is to be accompanied on his official visit by Minister of the Royal Palace Kong Sam Ol.

In a message to the nation on Tuesday, the King said his trip was made at the invitation of the Vietnamese government.

In his absence, Senate president Say Chhum, who is also the ruling Cambodian People’s Party deputy president, will be “acting Head of State”, the King added.

On his official Facebook page, Prime Minister Hun Sen wished the King a long life and “good health”, and explained that the purpose of the visit was to strengthen Cambodia’s relations with Vietnam.

“The visit of His Majesty [the King] to Vietnam this time is to promote a good relationship between both countries,” he wrote.

Hun Sen has previously stated his government’s support for the King, saying if people wanted to “destroy the monarchy, they will need to walk over Hun Sen’s dead body [first]”.

Cambodia and Vietnam first established diplomatic ties on June 24, 1967. A complex history – featuring occupations, conflict and numerous diplomatic tensions – have since put strain on the nations’ ties.

‘Spirit of friendship’

The King’s visit to Vietnam was made just two weeks after the prime minister led a senior delegation to the country, where he met with Vietnamese president Nguyen Phu Trong and National Assembly president Nguyen Thi Kim Ngan.

During Hun Sen’s visit to Hanoi between December 6-8, both countries’ leaders agreed to speed up the resolution to an ongoing land dispute over an unsettled 16 per cent of their 1,270km shared land border, saying they will complete the swift demarcation “based on the spirit of friendship”.

The government also signed six major documents with Vietnam, including an updated memorandum of understanding on transportation cooperation until 2025, amending a 2005 protocol.

Other amendments were made to a 2009 agreement on waterway transport, Cambodia-Vietnam border trade, the promotion of bilateral trade for 2018-19, an agreement on the prevention of cross-border crime and the return of items of national culture and heritage.