"Yes, we always monitor the situation. And Chairman Un [North Korean leader Kim Jong Un] has said that there would be something over Christmas. I think the president [US President Donald Trump] has engaged in personal diplomacy at a very high level with him over the years. And they have a good relationship personally. So perhaps he's reconsidered that. But we will have to wait and see. We're going to monitor it closely. It's a situation that concerns us, of course," O’Brien told ABC News in an interview.
He also said that the US could put extra pressure on North Korea, in case if Pyongyang would resume long-range missile tests or nuclear tests.
"You know, I don't want to speculate about what will happen. But we have a lot of tools in our toolkit, and additional pressure can be brought to bear on the North Koreans," O’Brien stated.
Earlier in December, the North Korean leadership promised a "Christmas gift," presumably meaning a long-range missile launch, to the US unless it changes its stance in the denuclearization talks. However, no movement has been reported from North Korea so far.