Transcript for Trump's stern warning to North Korea

In the meantime, president trump is dealing with yet another threat tonight, and this one, a far greater one. North Korea of course, testing that intercontinental ballistic missile. The distance proving that north Korea can likely reach the U.S. What will the U.S. Do? Tonight, the president in his own words, warning he is considering, quote, pretty severe things in response. Here's ABC's chief global affairs correspondent, Martha Raddatz. Reporter: While north Koreans today celebrated anew their country's breakthrough missile test with fireworks and dancing, president trump in Poland had a stern warning saying the world must confront the growing threat from that nuclear armed nation. I don't like to talk about what I have planned but I have some pretty severe things we are thinking about. That doesn't mean we are going to do them. I don't draw redlines. Reporter: Redlines or not the president made clear North Korea will not go unpunished. They are behaving in a very, very dangerous manner and something will have to be done about it. Reporter: But any military action taken by the U.S. Hitting north Korean airfields or missile facilities could prompt a catastrophic response. An attack on South Korea's capital or U.S. Military bases in the region. Defense secretary James Mattis today was stressing diplomacy. I do not believe this capability in itself brings us closer to war. We are leading in diplomatic and economic efforts. Reporter: The administration wants help in that from China, but president trump tweeted yesterday, trade between China and North Korea grew almost 40% in the first quarter. So much for China working with us. Today, ask about that -- Have you given up on president XI? Never give up. Saying he won't give up on China helping out. Martha with us live from our Washington bureau, and we heard secretary Mattis stressing diplomacy, but the president said on the world stage, he is considering pretty severe things in his words. This is a signal the white house and the Pentagon both know time is running out. Reporter: Kim Jong-un has to be reminded if he escalates this, he could indeed face a military response, but you are absolutely right, David. Time is running out because every day North Korea is working to perfect a nuclear missile capable of hitting the U.S., David. Martha, thank you. Here in New York City

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