"The United States will respond in a robust and meaningful way, when the Russian government engages in harmful activities," said US President Joe Biden as he kicked off his first overseas tour as president on Wednesday.
"We've already demonstrated that. I'm going to communicate that there are consequences for violating the sovereignty of democracies, in the United States, in Europe, and elsewhere," the US leader told US service personnel at Royal Air Force base Mildenhall in eastern England.
Biden's packed itinerary takes in a G7 leaders' meeting and a NATO summit before ending with a face-to-face with Russian President Vladimir Putin in Geneva on June 16.
About Putin, he said on Wednesday he will "let him know what I want him to know."
"We're not seeking conflict with Russia, we want a stable, predictable relationship," Biden added.
Biden hopes to leave behind the rancour and isolation of the Trump era on his first visit to Europe.
"At every point along the way, we're going to make it clear that the United States is back and democracies of the world are standing together to tackle the toughest challenges and the issues that matter most to our future," the US President said.
Biden is due to meet UK Prime Minister Boris Johnson on Thursday in Cornwall to discuss a new "Atlantic Charter," modelled on the historic agreement signed by Winston Churchill et Franklin D. Roosevelt in 1941.
Yet tensions may simmer beneath the surface of Biden's meeting with Johnson.
The US president opposed the Brexit movement that Johnson championed, and has expressed great concern with the future of Northern Ireland. Biden even once called the British leader a “physical and emotional clone” of Trump.
The British government has stressed Johnson’s common ground with Biden on issues such as climate change and his support for international institutions.
But Johnson has been frustrated by the lack of a new trade deal with the US.