Updated

North Korean dictator Kim Jong Un is reportedly growing “desperate” and is ready to strike the United States with a nuclear weapon, a defector from the regime said on Sunday.

Thae Yong Ho, the most senior North Korean defector in 20 years, told NBC News that Kim Jong Un is “desperate in maintaining his rule by relying on his [development of] nuclear weapons and [intercontinental ballistic missiles].”

“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,” said Thae, who defected in August.

Thae, who had served as North Korea’s deputy ambassador to the United Kingdom, said he was not directly involved in the dictatorship’s weapons program.

North Korea is believed to have several nuclear weapons; however, it is unknown if they could effectively use one to attack the U.S. In December, news emerged that North Korea could indeed attach a nuclear warhead to a missile -- but it did not appear the country could hit a target.

North Korea is now “fully equipped with nuclear attack capability,” Kim Jong Un announced after a submarine-launched missile in August.

Though he was believed to have been exaggerating, North Korea may have medium-range missiles capable of striking American military bases in the Pacific in the next couple years, experts say. Some believe Pyongyang may be able to hit the western U.S. as early as 2020.

North Korea continues to test ballistic missiles in provocative launches that have raised concerns among U.S. and Japanese leaders, among other nations.

The Associated Press contributed to this report.