"I don't think we can tolerate that risk. The world can't tolerate that risk. I mean, if North Korea has a nuclear weapon, I mean, who are you going to try to prevent getting one? Look at the behavior of this regime, the hostility of this regime to the whole world," US National Security Advisor Lt Gen HR McMaster told CBS News.
The United States, he said, is applying maximum pressure to North Korea to convince Kim Jong-Un that this is a dead end, this pursuit of nuclear weapons and an intercontinental ballistic missile- long range ballistic missile which of course poses a grave danger to the whole world.
"So what you've seen is an effort led by the President worldwide really though to isolate that regime, to cut off not just what is restricted by the current national -- the current UN Security Council resolutions but to do more," he said.
President Donald Trump has asked all nations to cut off all trade with this rogue regime which has never met a weapon it didn't use or proliferate or sell to somebody else, he said.
"You saw that with the cyber-attacks you just discussed and you saw it with the murder of Kim Jong Un's brother in a public airport with a banned nerve agent. So this is a regime that can't get this - this destructive capability," he asserted.
General McMaster said Mr Trump wants all nations to do more. It just doesn't make sense that Russia would increase trade and alleviate any pressure on the North Korean regime, he added.
Responding to a question, General McMaster said this is not the time to hold talks with the North Koreans.
"What he means is, there can't be negotiations under these current conditions. The north has to show initial steps toward denuclearization and the reason for this is previous approaches to negotiating with North Korea have failed miserably," he said.
"What the regime does is they enter into negotiations, all the while they continue these very destructive programs, these talks often times end in a -- in a weak agreement and then North Korea immediately violates that agreement. "The problem is now that their programs have advanced so far we don't have time to do that again and so we can't repeat the failed pattern of the past," the top official said.
General McMaster said Russia and the United States should cooperate on North Korea.
"There's no way that a nuclear armed North Korea is in Russia's interest and the President made that clear to President Putin on the phone call," he added.