Kim Jong Un‘s historic meeting with President Donald Trump will change the North Korean leader’s standing in the world, a specialist on U.S.-Korea relations said Monday.

“This is essentially the normalization of Kim Jong Un and North Korea on the international stage,” Scott Snyder, director of the program on U.S.-Korea policy at the Council on Foreign Relations, told CNBC’s “Worldwide Exchange.”

Snyder, also senior fellow for Korea studies at CFR, cautioned that “normalization” could come with “consequences.” Therefore, the Trump administration’s challenge will be to ensure the U.S. is not normalizing the isolated country as a nuclear weapons state, he said.

Earlier Monday, Secretary of State Mike Pompeo said the summit between Trump and Kim, which begins Tuesday in Singapore (Monday night EDT), is “truly a mission of peace.” He added that the United States is “eager” to see if Kim is “sincere” about denuclearization.

Sanctions on North Korea would remain in place until that had happened, Pompeo added. “If diplomacy does not move in the right direction … those measures will increase.”

Trump and Kim arrived in the Southeast Asian city-state on Sunday.

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Trump said over the weekend he’s confident “something positive will happen” and expects that “Kim Jong Un wants to do something great for his people, and he has that opportunity.”

The president has said he wants to strike a deal to get the North to give up its nuclear weapons.

John Park, director of the Korea Working Group and adjunct lecturer at the Harvard Kennedy School, told CNBC’s “Squawk Box” the summit is meant to get something on the table between the two counties. He said he expects more “ups and downs” following the meeting.

Park said the world will be watching for some sort of joint declaration between Trump and Kim as well as the official launch of the denuclearization of North Korea.