Donald Trump has dismissed DPRK's claim to be developing missiles capable of striking America.
In a tweet, the US president-elect derided the claim by DPRK's Kim Jong-un that preparations were in the final stage, saying: "It won't happen."
It was not clear if Mr Trump was expressing doubts about Pyongyang's nuclear capabilities or was planning preventative action.
Mr Trump also berated China for failing to help rein in its ally DPRK.
"China has been taking out massive amounts of money & wealth from the U.S. in totally one-sided trade, but won't help with DPRK. Nice!" Mr Trump tweeted.
"We would not agree with that assessment," US State Department spokesman John Kirby told reporters at a regular briefing on Tuesday.
A spokesman for China's foreign affairs ministry said Beijing's efforts on Korean peninsula denuclearisation were "perfectly obvious".
China had "proactively participated" in UN discussions and jointly passed several resolutions, the spokesman pointed out.
In a televised New Year message on Sunday, Mr Kim said DPRK was close to testing long-range missiles capable of carrying nuclear warheads.
He said the country was now a "military power of the East that cannot be touched by even the strongest enemy".
DPRKhas conducted two nuclear tests over the last year, raising fears that it has made significant nuclear advances.
But it has never successfully test-fired long-range missiles capable of carrying nuclear warheads.
Experts estimate it might take less than five years. UN resolutions call for an end to the country's nuclear and missile tests.
(BBC)