UK sovereign hails national friendship, but delivers pointed messages in speech during four-day US visit.

Britain’s King Charles III has used a speech in front of the United States Congress to pledge NATO unity and call for support for Ukraine amid Russia’s ongoing invasion.

The address on Tuesday came during the royal’s four-day visit to the US, with the US-Israel war with Iran, US President Donald Trump’s criticism of NATO, and trade tensions between the longtime allies looming large.

But Charles avoided any reference to specific frictions during his speech at the US Capitol, instead striking a light tone in his joke-heavy opening.

He praised what he called the shared history and values of the two countries, quipping at one point that Washington, DC was “a tale of two Georges”, the first US President George Washington and his ancestor, the UK’s King George.

He assured lawmakers, to laughs, he was not in the US “as part of some cunning rearguard action” in a delayed continuation of the Revolutionary War.

“I am here on this great occasion in the life of our nations to express the highest regard and friendship of the British people to the people of the United States,” the sovereign said to repeated standing ovations.

But amid broad themes of unity, more pointed messages lurked.

Charles did not directly address the US-Israel war with Iran or Trump’s outspoken criticism of NATO allies who have rejected joining Washington’s war efforts.

Instead, he praised support for NATO and the alliance’s invocation of its Article 5 collective defence treaty in the wake of the September 11, 2001 attacks.

“We answered the call together, as our people have done so for more than a century, shoulder to shoulder through two world wars, the Cold War, Afghanistan and moments that have defined our shared security,” he said.

He then turned to funding for Ukraine, an increasingly pointed issue in the Republican-controlled US Congress.

“Today, Mr Speaker, that same unyielding resolve is needed for the defence of Ukraine and her most courageous people,” he said, referring to House Speaker Mike Johnson.

In one instance, Charles hailed the “$430 billion in annual trade that continues to grow, the $1.7 trillion in mutual investment that fuels that innovation”.

Last week, Trump threatened to impose a “big tariff” on the UK if it did not drop a digital services tax on US tech companies.

At another point, Charles pointed to global environmental concerns.

“We ignore, at our peril, the fact that these natural systems, in other words, nature’s own economy, provide the foundation for our prosperity and our national security,” he said.

Trump has called climate change a “con job” and withdrew from the landmark Paris Agreement climate accords during his first and second terms. His administration has since pursued deregulation of fossil fuels and pivoted away from green energy, an approach embraced by many members of the president’s Republican party.

Other messages appeared to gently reference political trends in the US, where critics have accused Trump of using the Department of Justice for political retribution and of overturning long-standing norms of presidential authority.

Charles described the “common ideals” of the US and UK: “The rule of law, the certainty of stable and accessible rules, an independent judiciary, resolving disputes and delivering impartial justice”.

He also drew a throughline between the Magna Carta, the 13th-century document that established that the British king was subject to law, and constitutional and legal precedent in the US, calling it “the foundation of the principle that executive power is subject to checks and balances”.

The address came shortly before Trump was set to host Charles and his wife, Queen Camilla, for an official state dinner.

The pair were then set to visit New York and Virginia, before an official farewell ceremony at the White House on Thursday.