North Korea has tested a rocket engine that could be fitted to an intercontinental ballistic missile, a US official said, in an apparent provocation ahead of a summit between President Donald Trump and the leader of South Korea.
President Moon Jae-In heads to Washington next week to meet Trump for the first time since taking office in May, as tensions soar on the Korean peninsula over Kim Jong-Un's nuclear weapons programme.
The US official confirmed to AFP that Pyongyang tested a rocket engine on Thursday, on condition of anonymity and without providing further details.
Political science professor Yoo Ho-Yeol at Korea University said the test was "a carefully calibrated act of provocation ahead of the summit".
The North Korean regime will closely follow the meeting to gauge Seoul and Washington's future course of action concerning Pyongyang's pursuit of nuclear arsenal and missile development, he told AFP.
"The North has been building up missile capability for decades. The general consensus among experts here is that if left unchecked, the North would be able to have ICBMs in the near future", Yoo said.
Also Friday, Moon oversaw the test-firing of a home-grown missile with a range of 800 kilometres (500 miles).
The presidential Blue House said the South's test was meant as a warning against the North's provocative acts over the past months.
North Korea's last rocket engine test came in March and was apparently timed to coincide with the visit of US Secretary of State Rex Tillerson to Beijing, where he warned that regional tensions had reached a "dangerous level".
Rocket engines are easily re-purposed for use in missiles.
Outside observers say Pyongyang's space programme is a fig leaf for weapons tests.
The country's top newspaper Rodong Sinmun in May warned it was prepared to launch ICBMs at any time on orders from Kim.
The North has carried out two atomic tests and dozens of missile launches since the beginning of last year in its quest to develop a missile capable of delivering a nuclear warhead to the continental United States -- something Trump has vowed "won't happen".
- 'Top security threat' -
News of the recent test in the North came a day after Tillerson urged China, Pyongyang's sole ally, to put more pressure on the North to rein in its atomic weapons and ballistic missile programmes.
Calling North Korea the "top security threat" to the United States, Tillerson said China had a "diplomatic responsibility to exert much greater economic and diplomatic pressure on the regime if they want to prevent further escalation in the region".
China's top diplomat met Trump at the White House on Thursday, where he said Beijing was willing to keep working with Washington to defuse tensions on the Korean peninsula, China's foreign ministry said.
"China is willing to maintain communication and coordination with relevant parties including the United States to ease tensions on the peninsula," State Councillor Yang Jiechi said, according to the ministry.
Trump has made halting the North Korean nuclear threat his number one foreign policy priority.
In April, North Korea unveiled what could be a new ICBM at a giant military parade in a show of strength.