Transcript for North Korean official tells ABC News they want to talk only with U.S. about nuclear weapons

We heard the trump administration's take on the growing tensions of the north Korean nuclear program. This morning, Bob woodruff is reporting inside the reclusive country where he's just had a rare interview with a top thort Korean official for U.S. Affairs. Good morning, Bob. Reporter: Good morning, Martha. These tensions have never been as high. The top north Korean official that I spoke with told me he thinks there's a strong possibility for a preemptive strike against his country's nuclear program. He says that the army here is at the highest alert. Much of this because of that join South Korea and U.S. Military exercise nearby. And also, more nuclear assets in the peninsula. Considers about Rex tillerson's calling for an end to the policy of strategic patience with north Korea. He says it has failed. But Mr. Hon responds that the strategy to isolate North Korea has not worked and that it never will. He's never met president trump himself. He says he understands he's a good businessman. You have also very unpredictable. So they're preparing for everything. We will never know exactly what is happening behind the curtain here in Pyongyang. Only what we see on the rare trips inside the country. Certainly, the capital city right here is growing. A lot more construction. In fact, they are building entirely new neighborhoods that we have seen. In less than a year. We went to their new ski resort. Today, with beautiful construction and amazing lifts. But not many people are there. And despite all of the new sanctions by the U.S., China, the U.N., we didn't see anything getting worse. What they never show us is what is happening in the countryside. That is true. And impact on north Koreans who are living out there. What is obvious is that the u.s.-north Korea relationship has been getting worse. There's a lot of talking. In our interview, Mr. Hon's last words were interesting. He said if you bring out a knife to attack us, we'll take out a sword. If you come at us with a gun, we'll pull out a cannon. When it comes to diplomacy, while the trump administration talks about putting pressure on China to deal with North Korea, this top official says in terms of nuclear talks, North Korea only wants to talk to the united States. Martha? Thank you very much, Bob.

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