The nuclear-armed North has fired three banned missiles in the past five days, including an intercontinental ballistic missile test Pyongyang said showed its capacity for a "fatal nuclear counterattack on the hostile forces".

UN Secretary-General Antonio Guterres responded to Saturday's ICBM launch with a statement calling for Pyongyang to "immediately desist from taking any further provocative actions".

North Korea's vice foreign minister expressed "strong discontent and protest against the extremely unfair and imbalanced attitude" of Guterres, according to a statement carried by KCNA state media.

Kim Son Gyong said Guterres' assessment ignored "dangerous" joint military drills by Washington and Seoul and that he should "adopt a fair and balanced attitude".

Kim described North Korea's missile launches as a justified "countermeasure" to the recent US deployment of strategic bombers to the Korean peninsula.

Kim Yo Jong, the powerful sister of North Korean leader Kim Jong Un, had already said Pyongyang was closely monitoring moves by Washington and Seoul to deploy more US strategic assets to the region.

"The frequency of using the Pacific as our firing range depends upon the US forces' action character," she said in a statement on KCNA on Monday.

Relations between the two Koreas are at one of their lowest points in decades. North Korea declared itself last year an "irreversible" nuclear power and Kim Jong Un called for an "exponential" increase in weapons production, including tactical nuclear weapons.