John Bolton, former US Ambassador to the UN, said North Korea could also sell nuclear weapons to aspiring nuclear powers unless the rogue nation was stopped.
North Korea has continued with its development of a nuclear weapons arsenal despite international condemnation.
After the rogue state’s despot leader Kim Jong-un started a furious war of words with US President Donald Trump fears of the possible outbreak of World War 3 intensified.
Speaking on Fox News, Mr Bolton added his “preferred outcome” to the growing US-North Korea crisis would be to “reunite the two Koreas” but conceded talks with the hermit state would be a “complete non-starter”.
He said: “My preferred outcome is to reunite the two Koreas. That wouldn’t happen overnight.
“There are a variety of possibilities, one possibility is the Chinese said ‘we’re doing all we can, why don’t you sit down and negotiate with the North Koreans’, which is a complete non-starter in my view.
“I think then the outcome is nearly certain that North Korea will get nuclear weapons and not just North Korea since they’ll sell to anybody with hard currency, Iran, terrorist groups, other aspiring nuclear powers.
“That’s why the resolution of the North Korea issue is so important because the proliferation impact of North Korea visibly getting nuclear weapons around the world would be considerable.”
Mr Bolton said North Korea was “very close” to having the capability of striking “any” United States target with a deadly nuclear weapon.
The former ambassador said it remained unclear whether Mr Trump was able to secure an agreement with China to resolve the North Korea crisis.
Mr Bolton warned: “We don’t have a lot of time to wait around and find out.
“North Korea are very close now to being able to drop thermo-nuclear warheads on any target in the United States.