Boris Johnson said the inauguration of President Joe Biden and Vice President Kamala Harris was “fantastic” and a “step forward for the country that’s been through a bumpy period”.
The PM said it was the job of all UK prime ministers to have a “good, close working relationship” with US presidents.
Mr Johnson said he had a “fantastic joint common agenda” with President Biden on issues that “unite” the UK and the United States.
He added: “It’s a big moment for us. We have things we want to do together.”