Transcript for North Korea responds to Trump, rising tensions with the US

We are going to begin with tough comments from North Korea. A top official there says they will go to war if that's what the U.S. Wants. They are blaming president trump's aggressive tweets for escalating tension and Martha Raddatz just arrived in Seoul and, Martha, the entire region on edge right now. Reporter: That's right, George. North Korea could test a nuclear weapon at any time. It will most likely be tomorrow where there are celebrations in North Korea. This would be the sixth underground nuclear test for North Korea. But this is very different. They have made huge advances in their nuclear program and in their missile program and what else is different here, a trump presidency. This would be the first nuclear test under a trump presidency and he has already drawn a red line and the rhetoric is very hot, George. He has also put an aircraft carrier into the region. Some talk of a possible preemptive strike. Reporter: He has taken nothing off the table. A preemptive strike is, of course, a possibility but I think very unlikely with a nuclear test. But what's to look for, any time they test another missile, I suppose that is a possibility. And, Martha, this north Korean nuclear threat has bedeviled every single president going back to Bill Clinton. Reporter: It really has, George. There is not a lot different this time with the trump presidency other than the rhetoric and I think the danger here is some sort of miscalculation if the rhetoric gets too hot but president trump like any other president before him would like to solve this diplomatically with China's help. Okay, thanks to Martha for that. She will be anchoring "This week" Sunday morning from south Korea.

This transcript has been automatically generated and may not be 100% accurate.