"The secretary-general is very concerned about the acute risk of nuclear weapons being used," Dujarric said during a press briefing.
Dujarric stressed the importance of dialogue and diplomacy to move toward a nuclear-free world.
The remarks were in response to a reporter's question about a New York Times report that US President Joe Biden approved a classified US nuclear strategy plan that shifts focus to China, a country with significantly fewer nuclear warheads and a no-first-use policy.
The new strategy is also said to address concerns of potential coordinated nuclear challenges by China, Russia, and North Korea against the United States.
The document is highly classified and has no electronic copies, the report said. Biden is expected to provide a notification to Congress in connection with the revised strategy before leaving office, the report said.
The Chinese Foreign Ministry expressed concerns with the reports about the new US strategy. The US is promoting a "Chinese nuclear threat" to evade its nuclear disarmament commitments, the ministry said.