King Charles III visit live updates: Charles meets with top business leaders

Amid diplomatic tension between the U.S. and the U.K. over the war in Iran, President Trump spoke about the "special relationship" between the two nations.

"In the centuries since we won our independence, Americans have had no closer friends than the British," Trump said. "We share that same root. We speak the same language, we hold the same values, and together, our warriors have defended the same extraordinary civilization under twin banners of red, white and blue."

"What a beautiful British day this is," President Trump said as he kicked off remarks with thousands of guests gathered outside the White House South Lawn on a rainy morning in Washington.

The royals' state visit is to mark the 250th anniversary of American independence from Great Britain.

"Honoring the British king might seem an ironic beginning to our celebration of 250 years of American independence, but in fact, no tribute could be more appropriate," Trump said. "Long before Americans had a nation or a Constitution, we first had a culture, a character and a creed."

President Trump and King Charles are now reviewing the troops gathered at the White House, after performances by the U.S. Marine Band of "God Save the King" and "The Star-Spangled Banner."

King Charles and Queen Camilla have arrived at the South Portico of the White House for a formal state arrival ceremony. They are being greeted by President Donald Trump and first lady Melania Trump.

Notable officials are gathered on the White House South Lawn in rainy weather for the ceremony that will include a review of the troops, remarks by Trump and more.