North Korea has carried out successful ground tests of a new engine for its intercontinental ballistic missiles, improving the range of its nuclear deterrent, the regime said Saturday.
The jet test of a new type of high-power engine was ordered and attended at an unspecified date by leader Kim Jong Un, Pyongyang's Korean Central News Agency reported, according to the South's Yonhap News Agency.
The test's success "provided a firm guarantee for mounting another form of nuclear attack upon the US imperialists and other hostile forces," Kim was quoted as saying.
Now North Korea "can tip the new type of inter-continental ballistic rockets with more powerful nuclear warheads and keep any cesspool of evils in the earth including the US mainland within our striking range."
The isolated regime has nuclear bombs and ballistic missiles, but there have been doubts that the bombs are light enough or the missiles powerful enough for a viable nuclear warhead.
Kim in March said North Korea had developed a smaller warhead to fit on the intercontinental missiles, repeating a statement from a government representative last year.
The regime held its fourth nuclear test explosion in January, and launched a long-range rocket in February, prompting the UN Security Council to impose its strictest sanctions ever on Pyongyang.
In March, North Korea said it had tested a solid-fuel rocket engine, which would allow more frequent launches, according to a South Korean Defence Ministry spokesman.
Last month it also fired several short-range missiles into the sea, and threatened a pre-emptive nuclear strike in response to an annual US and South Korean military drill.
The recent announcements regarding the country's nuclear weapons programme could be to boost Kim's leaderhip ahead of a rare meeting of North Korea's ruling Workers' Party in May, Yonhap said, citing unnamed analysts.