"I don't want to rule out anything," he said on the Today show.
"It's a horror to use nuclear weapons. The power of weaponry today is the single greatest problem that our world has, and it's not global warming like our president said, it's the power of weapons – in particular, nuclear."
Trump added, however, that he "would be the last to use" nuclear weapons. "I will not be a happy trigger like some people might be, but I will never, ever rule it out," he said.
The billionaire businessman made similar comments to PEOPLE last month, saying, "I would be very slow on the draw. That would be such a last resort. I would be very, very slow. Slower than some of the people I see next to me."
Citing his opposition to the war in Iraq as proof that he would not be a trigger-happy president, he added, "Don't forget, I didn't want to go to Iraq. We made a terrible mistake going in."
Trump also recently said that he would not rule out using nuclear weapons in Europe. During a town hall in Wisconsin last month, he told MSNBC's Chris Matthews, "Look, nuclear should be off the table, but would there a time when it could be used? Possibly."
"I am not taking cards off the table," Trump added at the time.