One of the most high profile North Korean defectors in modern history warned the United States that the reclusive regime’s Supreme Leader Kim Jong Un was maintaining power through the development of intercontinental ballistic missiles capable of long-range attacks – and would use a nuclear bomb against the nation if he felt threatened.

Thae Yong Ho, a former North Korean diplomat who served as the North's deputy ambassador to the United Kingdom before defecting to South Korea with his family, said the supreme leader has been “desperate” to keep a grip on his power in recent months during an exclusive interview with NBC News Sunday.

Read: North Korea Will Launch Rockets 'At Any Time' Kim Jong Un Pleases, Officials Say

Tensions between the U.S. and North Korea have been high since the election of President Donald Trump last year. The north repeatedly launched ballistic missile tests in direct defiance of United Nations sanctions placed during former President Barack Obama’s tenure in office.

RTSCX0X North Korean leader Kim Jong Un watched the ballistic rocket launch drill of the Strategic Force of the Korean People's Army (KPA) at an unknown location, in this undated file photo released by North Korea's Korean Central News Agency (KCNA) in Pyongyang on March 11, 2016. Photo: Reuters

The U.S. has since retaliated with an essential show of force near the Korean peninsula, performing in a weeks-long trilateral military exercise operation with Japan and South Korea to prepare for potential missile threats from the north.

North Korea's Kim Jong Un is "desperate in maintaining his rule by relying on his [development of] nuclear weapons and ICBM (intercontinental ballistic missiles)," Yong Ho told NBC News’ Lester Holt Sunday. "Once he sees that there is any kind of sign of a tank or an imminent threat from America, then he would use his nuclear weapons with ICBM."

It remained unclear what exactly the North Korean leader determines to be an "imminent threat" from the U.S., though his regime has previously denounced the nearby trilateral military exercises as direct provocations of war. Secretary of State Rex Tillerson warned North Korea the U.S. was prepared to defend its South Korean and Japanese allies in the case of a preemptive attack from North Korea during his first mission to Asia in March.

Meanwhile, several North Korean missile tests have reportedly exploded or failed to launch, indicating the regime still has a long way to go before it can effectively target U.S. and South Korean military bases with total accuracy.