U.S. Secretary of State Mike Pompeo said Friday that he is "confident" there will be a third summit between President Donald Trump and North Korean leader Kim Jong-un and reaffirmed that sanctions will remain until North Korea's denuclearization.

Appearing on the U.S. TV show "This Morning" on CBS, Pompeo said he doesn't know when the third summit will happen but is hopeful it will be soon.

The secretary also said the two sides have been in contact since the summit in Hanoi, Vietnam, which he said led to a "deeper understanding" of each other's positions, and that the two leaders were able to make progress in that respect.

He added that the U.S. always knew nuclear negotiations were going to take a while.

Pompeo said the U.S. is determined and he is convinced North Korea is determined as well, saying that Kim promised Trump he will denuclearize. He said it's the mission of his team to make that happen.

Regarding the sanctions on North Korea, Pompeo said that Trump has been unambiguous and the administration's policy is incredibly clear, which is that economic sanctions and UN Security Council sanctions will not be lifted until the ultimate objective is achieved.