The report, prepared by independent sanctions monitors, claimed Pyongyang “produced fissile material, maintained nuclear facilities and upgraded its ballistic missile infrastructure” in breach of international sanctions.
The confidential report, seen by Reuters on Monday, said that the North had continued to seek technology for its nuclear programs from abroad.
North Korea has long been under harsh UN sanctions over its nuclear and missile programs. The US has spearheaded those sanctions and has imposed several rounds of its own.
The UN report also said that the North had displayed new short-range, medium-range, submarine-launched, and intercontinental ballistic missile systems at military parades.
According to the size of the missiles, the report assessed that “it is highly likely that a nuclear device” could be mounted on long-range, medium-range, and short-range ballistic missiles.
Pyongyang “announced preparation for testing and production of new ballistic missile warheads and development of tactical nuclear weapons,” it claimed.
The report, however, said it was uncertain whether Pyongyang “had developed ballistic missiles resistant to the heat generated during re-entry” into the atmosphere.
North Korea did not launch nuclear or ballistic missile tests in 2020. But the country’s leader Kim Jong-un has vowed to strengthen its military capabilities and place “the state defense capabilities on a much higher level, and put forth goals for realizing it.”
At a military parade in October 2020, Pyongyang showed off a new intercontinental ballistic missile, the first long-range weapon it had unveiled in two years.
And in a parade last month, the country displayed a submarine-borne ballistic missile that it said was “the world’s most powerful weapon.”
During the mid-January parade, Kim decried the US as North Korea’s “foremost principal enemy,” no matter who was president of the country.
His remarks came just days before Democratic President Joe Biden took the oath of office.
Former president Donald Trump met with Kim three times during his one-term presidency, but he refused to relieve any of the sanctions on North Korea in return for several steps taken by Pyongyang toward denuclearization, a key demand of the West.
That hampered further diplomacy between Pyongyang and Washington and prompted Kim to announce an end to a moratorium on the country’s missile tests.
Last week, South Korean President Moon Jae-in held his first telephone conversation with Biden, during which the two leaders agreed to draw up a joint “comprehensive” strategy on North Korea and cooperate to push for denuclearization of the country.
North and South Koreas are still technically at war as the 1953 Korean War ended with a truce and not a peace treaty.
President Moon formerly brokered the diplomacy between the US and North Korea.