The King says the UK and the US have an opportunity for partnership especially on security matters.

The United Kingdom recognises that the threats we face demand a transformation in British defence and as such the the UK is spending more on defence, he says.

Charles recalls how the UK stood besides the US in the aftermath of the September 11 terror attacks referring explicitly to Nato's Article 5 provision on collective defence.

He says he will be remembering the terror attacks on a visit to New York tomorrow.

"We stood with you then and we stand with you now in solemn remembrance of a day that shall never be forgotten," the King says to applause and yet another standing ovation.

The King refers back to his grandfather King George VI and his visit to the US in 1939 when “fascism was on the march”.

“Our shared values prevail,” the King says, adding that even though “we are in a more volatile and dangerous era” than in 1991 when his late mother Queen Elizabeth, spoke in this chamber.

The challenges we face are “too great for any one nation to bear alone." he says.

"But in this unpredictable environment, our alliance cannot rest on past achievements or assume that foundational principles simply endure.”

He quotes the British Prime Minister Sir Keir Starmer who said last month that the partnership is “indispensable” and we must build on it. This prompts a big round of applause.

Anthony Zurcher
North America correspondent

When King Charles noted the British legal tradition, enshrined in the Magna Carta, that “executive power is subject to checks and balances”, he received another standing ovation – with a twist.

The cheers started on the Democratic side of the chamber before spreading across the entire room.

Donald Trump’s critics on the left have frequently denounced the president for what they see as his abuse of power. It had been one of the motivating sentiments behind the “no kings” rallies that have drawn hundreds of thousands across the nation over the past year.

In this instance, it was a king’s line that gave Democrats in Congress a chance to again express their “no kings” sentiment.

Image source, Getty Images

The King continues with pointing to the similarities of the US and UK.

Referencing that it is still the season of Easter, the King describes it as the "season that strengthens my hope".

"It is why I believe that with all my heart the essence of our two nations is a generosity of spirit and a duty to foster compassion, to promote peace, to deepen mutual understanding and to value all people, of all faiths, and of none."

Members of Congress give the King another standing ovation.

The King continues by saying the alliance the two nations had built was "truly unique".

"In both of our countries, it is the very fact of our vibrant, diverse and free societies that gives us our collective strength, including to support victims of some of the ills that, so tragically, exist in both our societies today," the King says.

The King goes on to refer to the "strength" of his own Christian faith as a source of daily inspiration.

His reference to faith gets a gets big round of applause. He adds that he has dedicated much of his life to "interfaith relationships", which also gets big applause.

He also refers to the "profound respect that develops as people of different faiths grow in their understandings of each other".

Image source, Getty Images

The King calls the US founding fathers "bold and imaginative rebels with a cause".

He gives several examples of the ways the US government infrastructure is based on British tradition.

King Charles says they carried with them, and carried forward, "the great inheritance of the British Enlightenment", as well as the ideals which had an even deeper history: English Common Law and Magna Carta.

The King says the Declaration of Rights of 1689 "was not only the foundation of our constitutional Monarchy", but also provided the source of so many of the principles reiterated in the American Bill of Rights of 1791.

He adds that the US Supreme Court Historical Society has calculated that Magna Carta is cited in at least 160 Supreme Court cases since 1789.

Anthony Zurcher
North America correspondent

King Charles is getting a warm reception here at the Capitol so far.

The assembled Washington politicians and dignitaries are laughing at his jokes and, perhaps more importantly, they gave him a standing ovation when, quoting President Donald Trump, he says, “the bond of kinship and identity between America and the United Kingdom is priceless and eternal. It is irreplaceable and unbreakable.”

There may be tensions between the US and the UK at the moment, but the King appears to have successfully broken the ice on this occasion.

Image source, Getty Images

King Charles says this is his 20th visit to Washington DC.

He says the US Capitol symbolises the shared history between the two countries. He makes another reference to 1776, "or what Charles Dickens might have called ‘A Tale of Two Georges’".

The King references the first US President George Washington and his own five times great-grandfather King George III.

"King George never set foot in America and, please rest assured, I am not here as part of some cunning rearguard action!" he jokes, getting more laughs and applause.

Charles makes a reference to Trump's own state visit to the UK last year - quoting the president as saying: "'The bond of kinship and identity between America and the United Kingdom is priceless and eternal; it's irreplaceable and unbreakable.’"

His comments are received with a standing ovation from the US lawmakers.

Image source, Getty Images

The King goes on to say that we don't always agree - just see how the US was founded.

"With the spirit of 1776 in our minds, he says, we can perhaps agree that we do not always agree – at least in the first instance! Indeed, the very principle on which your Congress was founded – no taxation without representation – was at once a fundamental disagreement between us, and at the same time a shared democratic value which you inherited from us. Ours is a partnership born out of dispute, but no less strong for it," the King says.

"Our nations are instinctively like-minded", he says.

Drawing on these values and traditions, time and again, our two countries have always found ways to come together.

"Now we come together not just for the benefit of our people, but all people."

Image source, Getty

King Charles makes a lighthearted joke about the old tradition that "when I address my own parliament of Westminster, we still follow an age old tradition and take a member of parliament hostage".

Members of Congress chuckle at the joke, as King Charles continues.

"Holding him or her at Buckingham Palace until I am safely returned.

"These days we look after our guests rather well, often to the point that they do not want to leave.

"I don’t know Mr Speaker if there were any volunteers for that role today.”

The King's speech is punctuated with similar moments of levity.

The King goes on to say that he is the 19th "in our line of sovereigns to study, with daily attention, the affairs of America".

"So, I come here today with the highest respect for the United States Congress; this citadel of democracy created to represent the voice of all American people to advance sacred rights and freedoms."

He adds that he "cannot help but think" of his mother, Queen Elizabeth II, who addressed the same chamber in 1991, and that he has come to "express the highest regard and friendship of the British people to the people of the United" States.

King Charles says "we are meeting at times of great uncertainty" and references wars in Europe and the Middle East.

He mentions the incident over the weekend, where a man attempted to storm a gala event with weapons where Donald Trump was present.

"Whatever our differences, whatever disagreements we may have, we stand united in our commitment to uphold democracy, to protect all our people from harm," he says.

He adds: “Let me say with unshakeable resolve, such acts of violence will never succeed”

Image source, Getty Images

King Charles thanks US lawmakers and the American people for welcoming him on the 250th anniversary of the signing of the Declaration of Independence.

His reference to America's independence draws thunderous applause.

He says the destinies of the US and UK have been interlinked ever since.

"As Oscar Wilde said, 'We have really everything in common with America nowadays except, of course, language!'" The King jokes to laughter from his audience of officials.

After a brief introduction from Speaker of the House Mike Johnson, King Charles has begun speaking to the US Congress.

He is expected to call for "reconciliation and renewal" between the US and UK amid strained relations over the Iran war.

Watch live above.

The King has arrived in the House of Representatives chamber to applause from hundreds of onlookers, including top US officials.

He follows in the footsteps of his mother Queen Elizabeth II, who addressed the chamber in 1991.

Shaimaa Khalil
Reporting from Washington

The big waves of chatter in the chamber is punctuated by the gavel - one for House in order - then to call out congressional members of the escort committee who will welcome the King.

There’s a big buzz in the House chamber now as House and Senate representatives as well as invited guests make their way in and taking their seats from up in the gallery.

I can see Nancy Pelosi shaking hands and exchanging pleasantries and hugs. Everyone around me at the media gallery keep bringing up how this is what it’s like at the president's annual State of the Union - but this has a different feel as it’s like everyone here is putting on their finest, expecting a very special guest.

Albeit at very tense times

Vice President JD Vance and House Speaker Mike Johnson, presiding over the joint session of Congress, have named several senators and members of the House of Representatives who will escort the King into the chamber.

On the escort committee are Senate Majority Leader John Thune, Senate Minority Leader Chuck Schumer, and several others. They all left and will presumably return shortly alongside King Charles.

Members of President Donald Trump's cabinet also just walked into the room after being announced.

Anthony Zurcher
North America correspondent

The US can’t come close to the British level of pomp and circumstance, but a joint address to Congress is about the best that America can muster.

The chamber of the House of Representatives is already packed and buzzing – akin to the energy typically reserved for a presidential state of the union speech.

The stakes for King Charles, as has been noted, are high. The former Royal Navy helicopter pilot is on a rescue mission of sorts, trying to restore an Anglo-American alliance that has become strained of late.

The Capitol stage is set, and now it’s almost time for the king to make his pitch.