North Korean leader Kim Jong Un said Pyongyang would not hesitate to launch a nuclear attack if an enemy provokes it with nuclear weapons, state media reported on Thursday.

Kim made the remark as he met with soldiers working for the military's missile bureau and congratulated them over Pyongyang's recent launching drill of an intercontinental ballistic missile (ICBM), KCNA news agency said.

He said the test demonstrated the loyalty and strong stand of the armed forces and was "a clear explanation of the offensive counteraction mode and the evolution of the nuclear strategy and doctrine of the DPRK not to hesitate even a nuclear attack when the enemy provoke it with nukes", KCNA reported.

DPRK is the abbreviation for the North's official name, the Democratic People's Republic of Korea.

North Korea said this week it had tested its newest ICBM on Monday to gauge the war readiness of its nuclear forces against mounting US hostility.

The top diplomats of the United States, South Korea and Japan on Wednesday issued a joint statement condemning North Korea's recent ballistic missile launches and urged Pyongyang to engage in "substantive dialogue without preconditions".

Kim said Monday's launch showed the military's high mobility and rapid attack capability, and called for efforts to further strengthen its combat efficiency, KCNA reported.

In a separate statement, Kim's sister, Kim Yo Jong, condemned the United Nations Security Council (UNSC) for holding a meeting over the ICBM launch, saying it was an exercise of the country's right to self-defence.

"The UNSC should place heavy responsibility on the irresponsible behaviour and act of the US and the ROK, which have aggravated the tension on the Korean peninsula through all sorts of military provocations all year round," she said.

ROK stands for South Korea's official name, the Republic of Korea.

The United States, South Korea and Japan staged a joint air drill involving a US strategic bomber near the Korean peninsula on Wednesday, the latest US strategic asset to be deployed as part of Washington's pledge with Seoul to boost defence readiness.