Donald Trump
US President Donald TrumpReuters

South Korea on Friday rejected United States President Donald Trump's demand that Seoul should pay for a $1 billion anti-missile defence system. The US and South Korea are installing the Terminal High Altitude Area Defence (THAAD) system near the Korean peninsula to guard against potential nuclear threats from North Korea.

On Thursday, Trump had said that it would be "appropriate" for South Korea to pay for the "phenomenal" anti-missile system.

"I informed South Korea it would be appropriate if they paid. It's a billion-dollar system. It's phenomenal, shoots missiles right out of the sky," Trump was quoted as saying by Reuters.

The key parts of THAAD have already been delivered to South Korea. The move, however, has angered China who sees the advanced missile system as a threat to regional security balance.

The US and South Korea have argued that THAAD's installation is intended to guard against increasing missile threats from nuclear-capable North Korea. THAAD is an advanced weapon system designed to intercept and destroy short and medium-range ballistic missiles during their final phase of flight.

Top US officials have said that the missile system will be operational "within days."

South Korea and the US have been in a security alliance since the 1950-53 Korean War, and more than 28,000 US troops are stationed in South Korea.

The deployment of the missile system in South Korea has also sparked protests in the southern nation, where hundreds of residents, concerned over THAAD's potential impact on environment, took to streets, some even clashing with police.

TV footage showed large trailers in camouflage paint carrying some missile-related equipment entering a golf course in the southern county of Seongju on Wednesday, according to AFP.

Nuclear-power North Korea has issued multiple threats of attacks to the US, South Korea and Japan, issuing the latest against US last Sunday warning the nation that the North is ready to destroy a US nuclear-powered aircraft carrier deployed in Korean waters, with a single strike.

The country has carried out a total of five nuclear tests so far, and according to an expert satellite imagery analysis, Pyongyang may be preparing for a sixth test soon.