The surprise move comes less than a week after Trump accepted Kim's invitation to a summit on the regime's denuclearization.
Trump tweeted he will be replacing Secretary of State Rex Tillerson with Director of Central Intelligence Mike Pompeo.
"(Pompeo) will continue our program of restoring America's standing in the world, strengthening our alliances, confronting our adversaries, and seeking the denuclearization of the Korean Peninsula," he added in a statement.
A senior White House official who declined to be named said the president "wanted to make sure to have his new team in place in advance of the upcoming talks with North Korea and various ongoing trade negotiations."
Tillerson, the first secretary of state under Trump, advocated talks with Pyongyang as tensions heightened over its nuclear and ballistic missile tests last year.
|Outgoing US Secretary of State Rex Tillerson makes a statement on his departure from the State Department March 13, 2018 at the State Department in Washington, DC. (AFP=Yonhap)|
In October, Trump appeared to undercut his top diplomat, saying Tillerson was "wasting his time" trying to negotiate with Kim.
Pompeo has expressed a more hardline stance toward Pyongyang.
In an interview with Fox News Sunday, he defended the president's decision to meet with Kim, saying Trump "isn't doing this for theater, he is going there to solve a problem."
South Korea's national security adviser, Chung Eui-yong, said last week Trump had agreed to meet the North Korean leader by the end of May to achieve the permanent denuclearization of the regime.
Kim, according to Chung, had promised to commit to denuclearization, halt missile and nuclear tests and had expressed understanding that joint military exercises between South Korea and the US would continue -- key US demands.
The South Korean envoy met with Kim in Pyongyang last week.
Trump said Pompeo will be replaced by his deputy, Gina Haspel, making her the first woman to take the post.
"I've worked with Mike Pompeo now for quite some time. Tremendous energy, tremendous intellect, we're always on the same wavelength," the president later told reporters. "The relationship has been very good and that's what I need as secretary of state. I wish Rex Tillerson well."
Trump said he and Tillerson "disagreed on things," including the nuclear deal with Iran. With Pompeo, however, he said they have "a very similar thought process."
On his decision to meet with Kim, which would be the first summit between a sitting US president and a North Korean leader, Trump said he didn't discuss it much with Tillerson.
"I made that decision by myself. Rex wasn't, as you know, in this country. I made the North Korea decision with consultation from many people but I made that decision by myself," he said.
Tillerson was on a trip to Africa when the announcement was made Thursday. He later cut his tour short and returned to Washington early Tuesday, spurring speculation it was to prepare for the summit.
The former Exxon Mobil CEO said at a news conference at the State Department he would be delegating his responsibilities to Deputy Secretary of State John Sullivan at the end of the day and leaving office on March 31.
He also said the administration's "maximum pressure" campaign to increase economic and diplomatic sanctions on North Korea was a key accomplishment during his tenure.
"Working with allies, we exceeded the expectations of almost everyone with the DPRK maximum pressure campaign," he said, referring to North Korea by its official name, the Democratic People's Republic of Korea.
"With the announcement on my very first trip as secretary of state to the region that the era of 'strategic patience' was over ... we commenced the steps to dramatically increase not just the scope, but the effectiveness of the sanctions," he said, citing the North Korea policy of the Barack Obama administration.
The Trump administration has credited the campaign for nudging Kim to discuss denuclearization.
"The department undertook a global campaign to bring partners and allies on board in every country around the world, with every embassy and mission raising this to the highest levels, and in every meeting I've had throughout the year, this has been on the agenda to discuss," Tillerson added.
The nominations of both Pompeo and Haspel are subject to confirmation by the Senate. Pompeo, who was confirmed to be CIA director last year, is expected to be confirmed again after a hearing in April. (Yonhap)