United States forces on Friday opened their new headquarters in South Korea in what they called Washington’s biggest overseas base, weeks after President Donald Trump hinted that he wanted to bring the troops home.

The US and South Korea are treaty allies and for decades US Forces Korea (USFK) have been headquartered in Yongsan, central Seoul.

Both countries had agreed as long ago as 1990 to relocate the headquarters of the base to Camp Humphreys, an existing base in Pyeongtaek, around 60 kilometres south of the capital.

But the project was delayed for years by resident protests, financial issues and extensive construction work until 2013 when the first unit transferred across to Camp Humphreys, named after a pilot who died in a helicopter accident.

Apart from moving the USFK headquarters, the US-led United Nations Command, under whose flag the allies fought in the Korean War was also moved, with more units to follow suit later.

The US has 28,500 troops stationed in the South to defend it from the nuclear-armed North and the move comes only weeks after Trump and Pyongyang’s leader Kim Jong-Un had an unprecedented summit in Singapore.

At a press conference shortly after the summit, Trump had announced he would suspend joint military exercises with the South.

Camp Humphreys incorporates a total of 513 buildings including schools, shops and banks spread over 14.7 million square metres and will accommodate 43,000 people, including soldiers and their family members by the end of 2022.