"We can't tolerate that risk," he told CBS in an interview Tuesday morning. "If North Korea has a nuclear weapon, who are you going to try to prevent getting one? Look at the regime, the hostility of this regime to the whole world."
When asked whether Secretary of State Rex Tillerson's high-profile disagreements with President Donald Trump undermine him when working overseas, McMaster said no.
"The President has made very clear that on North Korea, for example, now is not the time to talk," McMaster responded. "And what he means is, there can't be negotiations under these current conditions. ... 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."
Tillerson said the White House has "not rejected diplomatic talks" with North Korea, but he agrees with the administration's belief that Pyongyang is not open to dialogue.
"What the White House has merely observed is North Korea has not exhibited a willingness to talk," Tillerson said during a press availability with Canadian Foreign Minister Chrystia Freeland in Ottawa.
Freeland officially announced Tuesday that the United States and Canada will co-host a January 16 meeting of foreign ministers from around the world in Vancouver, British Columbia, to discuss North Korea. The meeting will focus on ways to increase diplomatic pressure on Pyongyang.
"What's important for North Korea to know is this pressure campaign will not abate," Tillerson said. "We will not be rolling any of it back. It will only be intensified as time goes by, and it will remain in place until they agree to give up their nuclear weapons."
On Monday, White House homeland security adviser Tom Bossert said the US believes North Korea was behind the "WannaCry" cyber-attack
against the US and almost every other country in the world earlier this year.
And then on Tuesday during a briefing on the cyberattack he said the US does not have many more options -- "short of starving the people of North Korea to death" -- to punish North Korea for its behavior.
Asked about the consequences of North Korea's actions, Bossert said: "At this point, North Korea has done everything wrong as an actor on a global stage can do. President Trump has used just about everything you can use, short of starving the people of North Korea to death, to change their behavior. So we don't have a lot of room left here to apply pressure to change their behavior."
Tillerson also spoke
at a special meeting
of the UN Security Council on Friday, urging tougher international action to rein in Pyongyang and confronting North Korea's ambassador to the UN over his claims that the US is to blame for tensions on the Korean Peninsula.
Tillerson said the US would require Pyongyang to achieve a period of quiet before the US would engage in talks, clarifying confusion created earlier in the week when he said he would talk without preconditions
if North Korea were willing. That comment drew pushback from the White House.