SEOUL • Less than a week after US President-elect Donald Trump taunted North Korea over its ballistic missile capabilities, Pyongyang said it could conduct its first test of an intercontinental ballistic missile (ICBM) "any time and anywhere".

Although North Korea has vowed to develop the ability to attack the United States with nuclear warheads and has tested missiles that can reach throughout the Korean peninsula and its vicinity, it has never tested a long-range missile that could fly over the Pacific.

In a New Year's Day speech, North Korean leader Kim Jong Un said his country had reached a "final stage" in preparing to test an ICBM. That drew a tweet the next day from Mr Trump that said: "It won't happen!"

On Sunday, an unidentified spokesman of the North Korean Foreign Ministry told its official Korean Central News Agency: "The ICBM will be launched any time and anywhere determined by our supreme leadership."

The remarks were in response to comments last Thursday by US Deputy Secretary of State Antony Blinken, who said that North Korea had made "a qualitative improvement" in its missile capabilities over the past year and swore that Washington and its allies would continue "comprehensive, sustained pressure and sanctions".

Mr Ash Carter, the departing US Defence Secretary, said on Sunday that the US would shoot down a North Korean missile "if it were coming towards our territory or the territory of our friends and allies".

It remains unclear how close North Korea has come to building a reliable ICBM. Although it has displayed the road-mobile KN-08, believed to be its first ICBM, it has never flight-tested that system.

In the past year, however, North Korea has boasted of successfully testing key technologies, such as long-range missile engines and heat shields for an ICBM.

North Korea has sought to develop, by next year, miniaturised nuclear weapons that can fit atop a missile capable of reaching the US, according to defector and former diplomat Thae Yong Ho.

NYTIMES