The disarmament and peace institute at North Korea's foreign ministry issued the condemnation after Seoul and Washington wrapped up their 11-day annual 'Freedom Shield exercise' on Thursday.
The development comes as troops of South Korea and the US began their annual combined drills the 'Freedom Shield' exercise, which was paused after the accidental bombing of a civilian village by fighter jets last week.
The US on Monday (local time) raised concern over possible North Korea's 7th nuclear test and urged the international community to take concerted action in response to such a destabilizing event.
The missiles were fired from the 8.24 Yongung in waters off Kyongpho Bay in the East Sea in an underwater launching drill held at dawn Sunday, according to the official Korean Central News Agency (KCNA).