The Queen sent a private message to US president Joe Biden before he was sworn into office, Buckingham Palace has said.
The details of the message have not been released, but it is likely the head of state sent her good wishes to America’s new leader.
During the Queen’s 68-year reign, there have now been 14 American presidents – from Harry S Truman to Mr Biden.
A palace spokesman said: “Her Majesty sent a private message to President Biden ahead of the inauguration.”
With the world still battling the pandemic and the last state visit by a US president coming less than two years ago, when Donald Trump toured the UK in June 2019, it is unlikely an invitation to visit this year will be extended by the Queen to Mr Biden.
But the two heads of state could meet at some point when the G7 summit is staged in June in Cornwall. It is not thought the two world figures have met before.
The Duke of Sussex has known President Biden and First Lady Dr Jill Biden for a number of years, with the statesman and his wife supporting the royal’s Invictus Games for wounded, sick and injured veterans and serving military.
Harry met Mrs Biden at the Washington residence of Britain’s Ambassador to the US in 2012, and five years later the couple joined the duke at a wheelchair basketball match when the Games were staged in Toronto.
In the run-up to the November presidential election, Harry was accused of political interference after he urged people in the US to “reject hate speech” and vote in the presidential election.
He has moved to California with wife Meghan and son Archie to start a new life after the Sussexes stepped down as working royals for financial freedom.