The U.N. secretary-general is warning the U.S. and North Korea that "confrontational rhetoric may lead to unintended consequences" and stressing that the nuclear crisis must be solved diplomatically.

Antonio Guterres says it's "absolutely crucial" that the U.N. Security Council is united in dealing with North Korea's nuclear and missile tests and that the U.S., Russia, China, Japan and South Korea use one strategy.

Guterres told reporters at U.N. headquarters in New York on Tuesday that North Korea's nuclear and missile tests threaten regional and international stability.

He accused North Korea's leaders of "needlessly and recklessly (putting) millions of people at risk including its own citizens already suffering drought, hunger and serious violations of their human rights."

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Guterres urged communication and offered to support any efforts to peacefully resolve "this alarming situation."

Asked by CBS News if the U.N. could play a role in resolving the crisis in North Korea, the Secretary General said, "I have signaled to the parties my availability to support any serious efforts."

"Yet again, the DPRK [North Korea] has broken the global norm against nuclear test explosions," Guterres told reporters, CBS News' Pamela Falk reports, and he added that the unity of the Council is crucial in addressing this crisis.

But Russia's U.N. Ambassador Vassily Nebenzia made clear that disagreements persist in the Council about next steps, Falk reports. On Tuesday, he said that despite good intentions, sanctions are not working and that Moscow wants a new U.N. Resolution to focus more on a political solution, referring again to the China-Russia position in support of a "suspension for suspension."

Nebenzia also supported the Swiss proposal to mediate the dispute.

"The potential consequences of military action are too horrific," Guterres said.