“US heinous sanctions served as a catalyst and driving force that unleashed a gradual increase in our national strength,” state KCNA news agency cited a North Korean senior foreign ministry official as saying, referring to its nuclear tests prompted by international sanctions led by Washington.

“North Korea will protect its sovereign rights and security interests from increasing hostile threats and sanctions pressure from the United States, and take stronger real actions to make its already established military and technological strength irreversible,” the official added. Kim Yo Jong, the powerful sister of North Korean leader Kim Jong Un, said on Wednesday that the country would press on with its “overwhelming” military buildup in response to frequent US military drills with South Korea.