U.S. President Donald Trump remains optimistic about the prospects of North Korea's denuclearization and an invitation for nuclear inspectors to visit the country.

Speaking at a midterm election campaign rally in Missouri on Thursday, Trump said, "If you read the papers today, it came out to the surprise of a lot of people -- not a surprise to me -- that they don't mind having people come over, the experts, and check the sites." 

U.S. Secretary of State Mike Pompeo told a radio interview Wednesday that when he was with North Korean leader Kim Jong-un three and a half weeks ago, he committed to allowing American inspectors into two significant testing sites.

The two sites are believed to be the Punggye-ri nuclear test site and the missile testing facility in Dongchang-ri.

Trump said the U.S. hasn't taken sanction off North Korea but that hopefully, it will be able to down the road, adding "we want North Korea to be very successful."

He also boasted of his "very good" relationship with Kim Jong-un.

Trump said, "We are getting to a point where the North really wants to do something," and that there will be no worries about millions of lives being lost and nuclear weapons going up all over the place.

He went on to list the accomplishments so far, including North Korea's return of U.S. prisoners and remains of American soldiers from the Korean War, and highlighted the North has neither conducted nuclear tests nor missile launches.

Trump said past U.S. administrations failed to resolve the North Korea issue for a very long time and "we would be in a nuclear war right now if the right person didn't come along."