Tensions between the secretive communist state and the US have ratcheted up in recent weeks and the US leader recently boasted that he had dispatched an “armada” to the waters off the Korean peninsula.
Asked how worried Americans should be about the prospect of nuclear war, Mr Trump told US news channel TMJ4: "Look, you always have to be concerned.
"You don't know exactly who you're dealing with. I had a great, great meeting with the president of China and that meeting tells me a lot and you've seen a lot of things happen.
“They have a pretty good power, not a great power perhaps, but a pretty good power over North Korea. We're gonna see what happens. It's a very, very tricky situation."
Mr Trump blamed previous presidential administrations for creating the situation with North Korea.
He said the country should have been dealt with by President Obama and "previous presidents all the way back to Clinton".
He added: “Now I'm put in a position where he actually has nuclear and we're going to have to do something about it.!
Mr Trump said he was hopeful that North Korean leader Kim Jong-un wanted peace because that is what the US wanted, "but we're going to see what happens.”
The US has adopted a policy of "strategic patience" with North Korea.
But the Trump administration has made it clear this policy is now over, and has not ruled out military action.
On a recent visit to South Korea, Vice President Mike Pence said: “The era of strategic patience is over. President Trump has made it clear that the patience of the United States and our allies in this region has run out and we want to see change.
“We want to see North Korea abandon its reckless path of the development of nuclear weapons, and also its continual use and testing of ballistic missiles is unacceptable.”
Mr Pence also insisted that the long standing US commitment to South Korea against the North was “iron clad”.
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