Trump receives a personal message of congratulations from King Charles on his swearing-in.

Buckingham Palace confirmed that King Charles III sent a personal message of congratulations to President Trump on his inauguration.

A spokesperson for Buckingham Palace informed Planet Chronicle Digital that the message conveyed the "enduring special relationship between the U.K. and the U.S."

On Monday, Trump was sworn in for a second term as commander-in-chief at the Capitol Rotunda, marking a remarkable return to office.

Further details about the contents of the message have yet to be revealed.

King Charles has written to Trump before, specifically in July following the unsuccessful assassination attempt on his life in Butler, Pennsylvania.

Trump frequently expressed his admiration for the monarchy and referred to King Charles as "an excellent individual."

During his visit to the U.K. in 2019, President Trump expressed his admiration for Queen Elizabeth II, describing her as a "spectacular woman" and stating that he had an "automatic chemistry" with her.

Trump and Charles have a history of meeting.

Queen Camilla and Charles first met in 2005 during their visit to the U.S., and they crossed paths again at President George H.W. Bush's funeral in 2018.

In 2019, the two met to discuss climate change, and a scheduled 15-minute meeting lasted an hour and a half, according to Trump's comments at the time. He stated that Charles, a longtime environmentalist, "did most of the talking."

After their meeting, it was stated by Clarence House that Trump and Charles share a "good working relationship."

The likelihood of President Trump being invited to the U.K. for a state visit during his second term is uncertain, as reported by The Telegraph last month, due to the schedule of King Charles.

An invitation to attend the 250th anniversary of the signing of the Declaration of Independence in Washington, D.C. may be extended to King Charles and Queen Camilla next year.

Since his birth in 1948, King Charles has met 10 out of the 14 U.S. presidents who have served, as reported by the Associated Press.

In 1959, when Dwight Eisenhower visited Queen Elizabeth II and her family at Balmoral Castle in Scotland, the young boy checked off his first president. Tragically, the queen passed away on Sept. 8, 2022, after a 70-year reign. Following her death, Charles ascended the throne.

Charles did not encounter Harry Truman, Gerald Ford, Lyndon Johnson, or John F. Kennedy.

At the re-opening ceremony of Notre Dame Cathedral in Paris, President Trump and Prince William met and later had a sit-down meeting at the British Embassy.

At Notre Dame, Trump and William separately met with world leaders, including French President Emmanuel Macron and Ukrainian President Volodymyr Zelenskyy.

On Monday, President Trump received a video message of congratulations from U.K. Prime Minister Keir Starmer. In his message, Starmer highlighted the strong bond between the two countries and expressed his eagerness to enhance their partnership.

Starmer stated that for centuries, our two nations have had a bond of collaboration, cooperation, and enduring partnership. This bond is unique and he expressed this after meeting President Trump in September.

"We have collaborated to safeguard the world from oppression and strive for shared safety and prosperity."

This report was contributed to by Emily Trainham and Brie Stimson of Planet Chronicle, along with The Associated Press.