Joe Biden last night declared "America is back" as he arrived in Britain for his first trip abroad as US president.
The US president also declared that he wanted to see Vladimir Putin, the Russian president, face-to-face to "let him know what I want him to know."
Mr Biden will hold bilateral talks with Boris Johnson on Thursday before the three-day G7 leaders’ summit opens on Friday.
He will meet the Queen on June 13, then head to Brussels for Nato and US-EU summits early next week before an all-important first meeting with Mr Putin in Geneva on June 16.
Mr Biden said: "The United States is back and democracies of the world are standing together. We’re committed to leading with strength, defending our values and delivering for our people.
"No single nation can alone meet all the challenges we face. The world is changing. We’re in a different place than 10 years ago."
He added: "I believe we are at an inflection point in world history. We have to discredit those who believe the age of democracy is over. They’re wrong. Democracy doesn’t happen by accident. We have to defend it."
Mr Biden asked if "our British friends will excuse me" as he went on to quote the Declaration of Independence.
As he took the stage at RAF Mildenhall, Mr Biden told members of the military to be "At ease". He added: "I keep forgetting I’m president."
US President Biden delivers remarks to US Air Force personnel at RAF Mildenhall
Credit: BRENDAN SMIALOWSKI
G7 leaders from Canada, France, Germany, Italy, Japan, the UK and the United States meet this weekend for the first time in nearly two years
Credit: BRENDAN SMIALOWSKI
The president choked up as he talked about his son Beau, who deployed to Iraq and died of brain cancer in 2015 aged 46.
He said: "We owe you, we’re so damn proud of you, so proud…and I only wish my Major [his son Beau] was here to thank you as well. Mr Biden was introduced by the First Lady Jill Biden.
After telling the audience to be seated she saw her husband looking around the room She said: "Joe, pay attention" and Mr Biden saluted.
As Air Force One touched down ahead of the G7 summit it emerged that Mr Biden plans to donate 500 million Pfizer coronavirus vaccine doses to about 100 countries over the next two years.
The US will distribute 200 million shots this year, and 300 million in the first half of next year.
The vaccines will be given to 92 lower-income countries and the African Union, and will go through the COVAX vaccine alliance.
US national security adviser Jake Sullivan said Mr Biden was committed to sharing vaccines because it was in the public health and strategic interests of the US.
"We were the ‘arsenal of democracy’ in World War II," Mr Sullivan said. "We’re going to be the ‘arsenal of vaccines’ over this next period to help end the pandemic."
Moments before boarding Air Force One in the US Mr Biden had been asked if he had a "vaccine strategy for the world".
He said: "I have one and I’ll be announcing it."
Air Force One arrived at RAF Mildenhall on Wednesday
Credit: AP Photo/Matt Dunham
US president Joe Biden and first lady Jill Biden disembark Air Force One
Credit: REUTERS/Kevin Lamarque
Mr Biden also said he would rally democracies in an ideological and economic struggle against China and face down provocations from Russia as he left Washington on his first overseas trip as president.
"Making clear to Putin and China that Europe and the United States are tight," the president said when asked the goal of his busy trip.
The US president is eager to rebuild ties with allies after four years of strained relations and the hollowing out of multinational institutions under his predecessor’s "America First" agenda.
He will also announce a global coronavirus vaccination strategy, and seek to firm up consensus on climate change goals. But almost every policy sphere is overshadowed by what Mr Biden believes is a historic struggle between democracies led by the US and autocracies led by Beijing.
Part of the response Mr Biden is expected to push at the G7 is the idea of offering developing countries a “high standard alternative” to China for upgrading physical, digital and health infrastructure.
It would be the first explicit Western challenge to China’s "Belt and Road Initiative,” the massive infrastructure building program that has extended Beijing’s diplomatic and political clout throughout Africa, Asia, and Europe.
Mr Biden will also issue a stern warning to both Boris Johnson and the European Union not to "imperil" the Northern Ireland peace process.
While Mr Biden was on Air Force One over the Atlantic Mr Sullivan, said the president harbours "very deep" concerns on the issue.
Mr Sullivan said the president believes the post-Brexit Northern Ireland Protocol is "critical" to ensuring that the Good Friday Agreement is protected, as Britain and the EU try to resolve the issue of checks in the Irish Sea.
G7 Summit agenda
He said both sides must continue with negotiations, adding: "But whatever way they find to proceed must, at its core, fundamentally protect the gains of the Good Friday Agreement and not imperil that.
"And that is the message that President Biden will send when he is in Cornwall."
Mr Biden is proud of his Irish heritage and, according to aides, follows events in Northern Ireland very closely.
The first major test of Mr Biden’s renewal of US alliances will come in Geneva, when he sits down with Mr Putin for potentially adversarial talks on a string of mutual grievances.
President Joe Biden’s European tour itinerary
US and Russian officials have both said in recent weeks that they do not expect any significant breakthrough from the meeting.
Rather, the summit is seen as a chance to reopen a channel of communication with the Russian leader and make America’s intentions clear on issues including the war in Ukraine, election interference, and cyberattacks by Russia-linked hackers.
A number of organisations including one of the world’s largest meat suppliers, a major US fuel pipeline, and Ireland’s public health system have been crippled by ransomware attacks in recent weeks.
Mr Biden is expected to express his frustration that Mr Putin has allowed hackers operating within Russia to act with impunity.
Asked if he and Mr Putin would be able to work out any kind of understanding on cyberattacks, he paused and then said: "Who knows at this point. It’s going to be a subject of our discussion.”