In both the New Atlantic Charter agreed by Biden and British Prime Minister Boris Johnson, as well as the joint statement from the US and the European Union, all parties agreed that if the democratic rules-based international order is to thrive in a world of rising autocracies, the rules created by the West "need an update."

In a speech delivered at NATO headquarters in Brussels, the commander-in-chief of the world's most advanced army said, "We have to prove to the world and to our own people that democracy can still prevail against the challenges of our time and deliver for the needs of our people."

European diplomats said there is a new awareness that the US and other countries could again see the rise of populist movements that were seen to stymie international cooperation and in some places, undermine democracy -- and that fueled a desire to find agreement and create "irreversible" progress.

"We saw what happened with the US election, we know it can also happen in our democracies too, sadly, it's something that has in a way happened in the UK with Johnson and the Brexit.

It's something that has happened in France with the Yellow Jackets," said one European diplomat, referring to populist movements in Europe.

Pointing to Biden's five different engagements over the week -- meetings in the UK, the G7, meetings with the EU and NATO, then the summit with Russian leader Vladimir Putin -- a second European diplomat said the US carefully constructed the week to deliver and emphasize that message.

"All of [the events] carefully built on each other to send the same message: the US is back, the US is returning to the fold of democracies, and it's committed to leading them."

Pointing to Biden's five different engagements over the week -- meetings in the UK, the G7, meetings with the EU and NATO, then the summit with Russian leader Vladimir Putin -- a second European diplomat said, "all of them carefully built on each other to send the same message: the US is back, the US is returning to the fold of democracies, and it's committed to leading them."

This sort of pro-West, pro-democracy rhetoric is absolute catnip to European leaders, many of whom like to believe they are the closest ally of the most powerful nation on earth.

"It's not implausible, given US sentiment to China, that it will affect how willing American officials are to work with Europeans on key future technologies like artificial intelligence, given American concerns over China's record on intellectual property theft and security concerns."

Brexit continues to divide

Another issue blighting Europe and likely to get out of hand very soon is the post-Brexit spat over Northern Ireland -- which Biden has personally commented on more than once.

Reviewing the areas where the US and Europe do have differences, a third European diplomat said, "the idea was not to fix all the problems in one week.

it was to lay the foundations and the technical work that needs to be done in order to sit at the table and address the issues in a cooperative approach, not a confrontational approach, that allows things to move forward."

While no one doubts that the spirit of cooperation and renewal on display between Biden and allies this week was sincere, the time frame for meaningful, lasting change is tight.

"The window of opportunity to show that America is back is small, with the US mid-terms being next November," says Georgina Wright, an expert in European politics at the Institut Montaigne in Paris.

Steven Blockmans, acting director of the Centre for European Policy Studies, agrees that the words are sincere, but action could be difficult.

"The question of whether the jet-setting recovery tour will amount to more than just a sugar rush for transatlantic relations depends on the West's ability to translate summit conclusions into concrete initiatives," he says, adding that "Europeans will need time to gain confidence about the health of US democracy and that America is not just back but also here to stay."

For the time being, European officials are delighted with what they perceived to be a Biden love-bombing.