Washington CNN  — 

North Korea has invited President Donald Trump to meet their leader Kim Jong Un according to a senior US official and a former US senior official.

Trump told reporters Thursday that South Korea will make a “major announcement” concerning North Korea at 7 p.m. ET.

On Thursday a South Korean delegation came to the White House to brief officials on its most recent talks with North Korea – the most significant talks between the two countries in more than a decade.

The South Korean officials visiting the White House on Thursday talked to Trump, a person familiar with the matter said.

They delivered a letter from Kim to Trump inviting him to meet, according to a senior US official and a former US senior official. A senior administration official later told reporters that the message and invitation from Kim to Trump was not in a physical letter, but conveyed “orally” by South Korea’s Chung Eui-Yong.

“This was a message conveyed orally by Kim to the national security adviser of South Korea,” the official said.

The senior US official said North Korea has offered to suspend their nuclear missile testing alongside their invitation for talks. The official also said there are no plans to suspend the upcoming planned military exercises with South Korea.

It’s not clear if the South Koreans spoke to the President before or after his surprise pop-in to the White House briefing room.

The leader of the South Korean delegation, Chung Eui-yong, will make the announcement from the stakeout position outside the West Wing, according to White House press secretary Sarah Sanders. He will be flanked by rest of the South Korean delegation.

National security adviser Lt. General H.R. McMaster will brief the UN Security Council on Monday regarding the situation in North Korea and the talks with the South Korean delegation, according to a senior US official.

Trump has expressed an openness to dialogue with North Korea, but the Trump administration has said North Korea must first take concrete steps toward denuclearization.

“All options are on the table and our posture toward the regime will not change until we see credible moves toward denuclearization,” a senior administration official told reporters on Tuesday. “What we are looking for is concrete steps toward denuclearization.”

Trump’s approach to North Korea has wavered between bellicose rhetoric and expressions of openness to diplomacy – with the President saying the US would rain “fire and fury” on North Korea one day and then saying he would consider speaking directly with the country’s leader, Kim Jong Un, under the right circumstances.

Amid the potentially breakthrough talks between North and South Korea, the Trump administration has also credited its campaign of “maximum pressure” on North Korea as having brought Pyongyang to the negotiating table.

Since Trump came in to office, the US has leveled some of its most significant and far-reaching sanctions against North Korea and has also succeeded in pressuring China to further isolate the regime.

CNN’s Will Ripley, Kevin Liptak and Michelle Kosinski contributed reporting.

This story has been updated.