President Donald Trump called on allies on Thursday to take action against North Korea's missile threat.

Speaking in Warsaw, Poland, where Trump is meeting with his NATO partners, the U.S. president said North Korea is behaving in a "very, very dangerous manner" and that something needs to be done about it.

"It's a shame they're behaving this way, they are behaving in a very, very dangerous manner and something needs to be done about it," he said.

Trump didn't reveal what the U.S. plans are, but he described them as severe. He added that the U.S. will evaluate the issue in the coming weeks and months and react accordingly. "I don't like to talk about what I have planned, but I have some pretty severe things that we're thinking about," he said.