In a shocking announcement Thursday night, South Korea's national security adviser Chung Eui-yong said President Trump has agreed to meet with North Korean leader Kim Jong Un, and the North is "committed" to denuclearization. The intended meeting -- confirmed by the president and White House press secretary Sarah Huckabee Sanders -- is supposed to take place by May, but a time and place have yet to be decided.

Chung said Kim "expressed his eagerness to meet President Trump as soon as possible. President Trump appreciated the briefing and said he would meet Kim Jong Un by May to achieve permanent denuclearization."

Chung also said Kim agreed to refrain from nuclear testing, and routine joint military exercises will continue as planned. "I told President Trump that in our meeting, North Korean leader Kim Jong Un said he's committed to denuclearization," Chung said. "He pledged that North Korea will refrain from any further nuclear or missile tests."

Chung thanked Mr. Trump, Vice President Mike Pence, the national security team and National Security Adviser H.R. McMaster, saying that Mr. Trump's leadership and his pressure policies, along with "international solidarity," led to this juncture.

Get Breaking News Delivered to Your Inbox

Mr. Trump tweeted that a meeting is "being planned," and sanctions will remain in place until an agreement is reached.

Kim Jong Un talked about denuclearization with the South Korean Representatives, not just a freeze. Also, no missile testing by North Korea during this period of time. Great progress being made but sanctions will remain until an agreement is reached. Meeting being planned! — Donald J. Trump (@realDonaldTrump) March 9, 2018

On a last-minute conference call with reporters, a senior administration official said Mr. Trump was briefed by South Korean president Moon Jae-in, along with other South Korean and U.S. officials. The official, asked about the possibility of inspections, said any deal with North Korea would have to come with some form of verification of denuclearization.

South Korean National Security Adviser Chung Eui-yong (C) briefs reporters outside the West Wing of the White House on Thu., March 8, 2018, in Washington, D.C., announcing North Korean leader Kim Jong Un has offered to meet President Trump. Getty

The announcement was made at the White House after Mr. Trump unexpectedly walked into the White House briefing room Thursday and told reporters that South Korea would be making a major announcement at 7 p.m. He added that he has spoken with Moon. The president rarely -- if ever -- appears in the briefing room, tipping off reporters to how momentous the announcement must be.

"South Korea is going to be making a huge statement tonight on a big subject ... on a big subject ... on North Korea," said Mr. Trump, according to CBS News' Jacqueline Alemany. Journalists were instructed by the president to turn off their cameras.

South Korean officials who met with Kim this week were to meet with Mr. Trump Thursday, the Reuters news agency reported, citing a South Korean presidential official. McMaster met Thursday afternoon with his South Korean counterpart Chung to be briefed on North Korea's offer, according to a White House official.

On Tuesday, South Korea said that the North had agreed to impose a moratorium on tests of nuclear weapons and missiles if it holds talks with the United States. South Korea's presidential national security director said Tuesday that North Korea said it's ready to have "heart-to-heart" talks with the United States on issues regarding the North's potential denuclearization and the normalization of relations between Pyongyang and Washington.

CBS News' Margaret Brennan contributed to this report.