The announcement of the timing for the first meeting between the two leaders came just three days after Mr Trump hosted a senior North Korean delegation at the White House bearing a letter from Mr Kim. "They are loyal to Kim Jong Un and no one else". South Korean government ministries did not confirm or deny it.
U.S. officials believe there has been some dissent in the North Korean military about Kim's overtures to Seoul and Washington.
Robert Menendez (D-N.J.), the ranking member of the Senate Foreign Relations Committee, said Monday - noting how North Korea had signed memorandums with the United States in the past that then fell apart.
It is unclear whether Kim Jong-un is removing hardliners - who dominated military policy previous year, when Pyongyang-Washington tensions were at their apex - from the high command ahead of his upcoming summit with Donald Trump, or is simply replacing old figures.
It is now led by General Kim Su Gil with Son Chol Ju as his deputy.
The Yonhap report did not address the current health and happiness levels of the three top leaders who were displaced.
Trump pardons conservative, says lifestyle maven Stewart may be next
The President did not use the Office of the Pardon Attorney for the pardons for Arpaio or Libby. On Wednesday, Trump met with Kim Kardashian to discuss prison and sentencing reform.
The moves are likely meant to surround Kim with a younger, even more trusted cohort of officials whom he can rely on as he confronts a slew of domestic and global issues, said Michael Madden, a North Korea expert at Johns Hopkins University's 38 North website.
Both countries have faced worldwide isolation - North Korea over its nuclear weapons program, and Syria over its tactics during its bloody civil war. But she said there has been no change in what Trump has described as a "maximum pressure" campaign on the North Korean regime.
There are also suggestions that the North Korean leader is acting out of concern that disgruntled military officers might attempt a coup when he travels to Singapore later this week for a summit with Donald Trump.
All of the newly promoted officials are younger than their predecessors, even though they are all in their 60s.
There has also been speculation Kim does not wish to leave North Korea for an extended period of time as this may encourage any remaining opponents to his rule to seize the opportunity to stage a coup.