MOSCOW (AFP) - North Korea is ready to deliver the "most ruthless blow" if provoked by the United States, its ambassador to Moscow said Thursday (April 6).

"Our army has already said that if there will be even the smallest provocation from the United States during exercises, we are ready to deliver the most ruthless blow," Interfax news agency quoted ambassador Kim Hyong Jun as saying, adding that his country had the "readiness and ability to counter any challenge from the US."

Trump on Wednesday pledged to Japanese Prime Minister Shinzo Abe that the US would "continue to strengthen its ability to deter and defend itself and its allies with the full range of its military capabilities," a day after Pyongyang fired a ballistic missile into the Sea of Japan (East Sea).

North Korea's foreign ministry on Monday assailed Washington for its tough talk and for an ongoing joint military exercise with South Korea and Japan which Pyongyang sees as a dress rehearsal for invasion.

The "reckless actions" are driving the tense situation on the Korean peninsula "to the brink of a war", a ministry spokesman was quoted as saying by the official KCNA news agency.

The idea that the US could deprive Pyongyang of its "nuclear deterrent" through sanctions is "the wildest dream", it said.

The US military said Tuesday that nuclear-armed North Korea had fired a ballistic missile into the Sea of Japan but that it did not represent a threat to North America.

Pyongyang is on a quest to develop a long-range missile capable of hitting the US mainland with a nuclear warhead, and has so far staged five nuclear tests, two of them last year.