President Donald Trump called the news that North Korea is willing to talk to the United States about giving up its nuclear weapons "very positive" and said he was open to talks with Pyongyang during an Oval Office meeting with his Swedish counterpart on Tuesday.
"They seem to be acting positively. We're going to see," Trump said.
But a senior administration official sounded a note of caution after the President spoke, saying the US is looking for North Korea to take concrete actions or "credible moves" toward denuclearization before agreeing to direct talks.
"All options are on the table and our posture toward the regime will not change until we see credible moves toward denuclearization," the official said. "What we are looking for is concrete steps toward denuclearization."
The senior administration official signaled a North Korean pledge to stop testing nuclear weapons and ballistic missiles would not suffice if North Korea privately continues to develop its nuclear and ballistic missile programs.
"If their plan is simply to buy time in order to continue building their arsenal, talks aren't going to get far at all because we've seen that movie before, we've seen it several times and we are not about to make the latest sequel in what would be a very bad ending," the official said.
"I think that their statement and the statements coming out of South Korea and North Korea have been very positive. That would be a great thing for the world. So we'll see how it all comes about," the President said earlier.
He repeated his assertion that the problem should have been solved by prior presidents but said the nuclear standoff should end.
"We cannot let that situation fester. We cannot let it happen," he said.
Trump then went on to call North Korea's participation in the Olympics "terrific," saying it lent a sense of momentum to the situation.
"Hopefully, we'll go in the very peaceful, beautiful path. We are prepared to go whichever path is necessary. I think we are having very good dialogue. You are going to certainly find out pretty soon what's happening," he said.
Earlier on Tuesday, Trump hailed "possible progress" in talks between North Korea and South Korea, hours after the US ally said that North Korea is willing to talk to the United States about giving up its nuclear program.
"Possible progress being made in talks with North Korea. For the first time in many years, a serious effort is being made by all parties concerned. The World is watching and waiting! May be false hope, but the U.S. is ready to go hard in either direction," Trump tweeted.
North Korean leader Kim Jong Un has also agreed to refrain from conducting nuclear and missile tests while engaging in dialogue with the United States, Seoul's national security chief Chung Eui-yong said after returning from talks with Kim. Chung said Pyongyang expressed willingness to talk to the United States "in an open-ended dialogue to discuss the issue of denuclearization and to normalize relations with North Korea."
Chung will travel to the United States "sometime this week," a spokesperson for the South Korean presidential office tells CNN.
US Director of National Intelligence Dan Coats expressed his skepticism of North Korea's intentions during a hearing at the Senate Armed Services Committee on Tuesday, saying that past failed efforts have allowed North Korea to continuing to develop their weapons program.
"Maybe this is a breakthrough. I seriously doubt it," Coats said. "But like I said, hope springs eternal."
During the same hearing, Defense Intelligence Agency Director Lt. Gen. Robert Ashley told lawmakers he is not optimistic about North Korea's recent overtures.
Sen. James Inhofe, R-Oklahoma, said he was "somewhat optimistic" about the latest developments and asked Ashley: "Do you share my somewhat optimistic view of what happened, general?"
Ashley responded, "right now, I don't share your optimism. That's kind of a 'show me' and so we'll see how this plays out."
Vice President Mike Pence also weighed in with a cautiously optimistic statement of his own on Tuesday in which he reaffirmed the US' commitment "to applying maximum pressure on the Kim regime to end their nuclear program."
"Whichever direction talks with North Korea go, we will be firm in our resolve," Pence said. "All options are on the table and our posture toward the regime will not change until we see credible, verifiable, and concrete steps toward denuclearization."
The Trump administration, which has aggressively pursued sanctions against North Korea, has said it won't meet with the regime unless it abandons its nuclear program. Moon has previously called on the US to ease its position on preconditions for talks.
Last month, it was revealed that Pence was set to meet with North Korean officials, including Kim Jong Un's sister, during their visits to the Winter Olympics in South Korea. But the North Koreans pulled out of the planned session before it could happen.
Latest US intelligence assessments about North Korea's nuclear ballistic missile program show that Kim's regime has continued to make progress during the last few months on improving the guidance of their missiles that would allow them to hit specific targets, an administration official with knowledge of the information told CNN's Barbara Starr.