SEOUL Isolated North Korea stepped up its war of words against the United States on Tuesday, vowing to boost its nuclear deterrent after Washington warned Pyongyang of further sanctions if it did not abandon its atomic program.
The North's foreign ministry spokesman said via the official KCNA news agency that it would "bolster its nuclear deterrent as long as the United States was continuing with its hostile policies" and that it planned "countermeasures" following pressure from Washington.
Last week, world leaders meeting in the United States said the isolated North needed to adhere to international norms on nuclear issues and said it would face more isolation if it "continues down the path of provocation".
Under new leader Kim Jong-un, North Korea launched a long range rocket in April, breaking an agreement with the United States that would have traded food aid for access to its nuclear facilities, among other things.
Many experts now believe the reclusive North is preparing for a third nuclear test, and could even use highly enriched uranium for the first time. Experts say the North already has enough fissile material from plutonium for at least six nuclear bombs.
U.S. Special Representative for North Korea Policy Glyn Davies told reporters in Seoul on Monday that North Korea could expect "a swift and sure" reaction by the international community if it undertook further hostile actions.
Davies was holding talks with his Chinese counterpart in Beijing on Tuesday.
China is North Korea's sole major economic and diplomatic backer and even it has put pressure on Pyongyang to back down on plans for a nuclear test.
Yang Moo-jin, a professor at the University of North Korean Studies in Seoul, was skeptical that the latest rhetoric from Pyongyang signaled a nuclear test was imminent. "North Korea is simply saying: Don't agitate or provoke us," he said.
Recent satellite imagery published by IHS Jane's Defense Weekly, a specialist defense publication, showed there had been more work at the site of previous nuclear tests that could indicate the North was preparing for its third nuclear test.
The Janes analysis showed mining carts and excavation equipment as well more debris from inside a tunnel that could be used for a third nuclear test.
"A third nuclear test by North Korea would be the latest move in restarting its nuclear weapons program, which it agreed to mothball in a 29 February deal with the U.S.," said Janes analyst James Hardy.
Since the death of Kim Jong-il in December, Kim Jong-un, believed to be in his late 20s, has shown he will continue with his father's hardline "military first" policy.
(Reporting by Ju-min Park; Editing by David Chance and Jeremy Laurence)