Image copyright AFP Image caption The Trumps will watch the Bastille Day parade on the Champs-Élysées

Not long ago Donald Trump said that Paris was a terrible place. Now he's embraced the city and the nation, strengthening US-France relations.

On Thursday morning Mr Trump wore a crisp white shirt, cufflinks and a gold-coloured belt buckle that gleamed. He and the First Lady were arriving in Paris for Bastille Day. On the tarmac at Orly, he kissed his wife on both cheeks, and they headed for separate cars. It was all very French.

"A fun trip," one of his aides told me on Air Force One while we flew across the Atlantic. It was a journey that had once seemed unimaginable - and showed how the president's views about the city have changed since the presidential campaign.

More importantly, his trip was ushering in a new age of US-France relations, a transatlantic partnership that has roots in the history of both countries.

Brief respite for Trump

During his two days in Paris, Mr Trump will spend time with Emmanuel Macron, the French president, and dine in a restaurant in the Eiffel Tower. He will watch the Bastille Day parade on the Champs-Élysées.

This year marks the 100th anniversary of US forces entering World War One, and for this occasion US and French troops will be marching together in the parade.

During the trip the US president will also have a chance to escape the controversies over Russia and other issues that have dominated the news cycle in Washington.

Image copyright Reuters Image caption The American first couple arrived in Paris early on Thursday

It is easy to understand why he would want to get away from Washington. Still the decision to visit Paris and not another city was unexpected - for just about everybody.

Mr Macron invited him several weeks ago, and Mr Trump "was very excited to respond and to accept the invitation," said a senior administration official. It was a surprising development - particularly since the US president had just pulled out of the 2015 Paris climate accord.

Until recently he had a negative view of the city. "Paris is no longer the safe city it was," he said on MSNBC in 2015. "They have sections in Paris that are radicalised, where the police refuse to go there. They're petrified."

During the presidential campaign, he said that a friend, Jim, had visited France and told him not to go there. "France is no longer France," said Mr Trump, quoting "Jim".

He had little evidence for these remarks. Now he seems to have forgotten about them. This morning at the airport he seemed to be having fun.

Rocky past

White House officials said that during the visit Mr Macron was likely to bring up the issue of the environment, and that the two world leaders would discuss the matter. They will also talk about Syria as well as about their shared military history.

The relationship has had its ups and downs.

Under President George W Bush, US-France relations hit a rocky period. Many people in the US criticised the French because they did not support the Iraq war, and some US restaurants stopped serving French fries as a protest against the French nation. "Freedom fries" were offered, and breakfast on Air Force One featured "'freedom toast" instead of French toast.

Image copyright Reuters Image caption President Trump angered many in France when he called Paris "unsafe" two years ago

Over time, though, the two nations and their militaries drew close again. Presidents Trump and Macron will build on this relationship, one that allowed the US and France to work together in the campaign against the Islamic State group.

"There were kinks that needed to be worked out in terms of intelligence sharing," said Charles Kupchan, who served as the national security council's senior director for European affairs during the Obama administration. "But the relationship between the US and the French military is extremely close."

Now the relationship is entering a new phase - one in which the French language and culture are celebrated, however briefly. One of President Trump's aides tried gamely to say a few words in French while we flew on Air Force One. Freedom toast is a thing of the past. Spinach quiche, decorated with fresh blackberries, were served for breakfast.

In the end, it is hard to explain the shift in Donald Trump's views of France, and why he has warmed up to Paris. He sometimes acts impulsively and does not fully explain why he has done something. Still he and his aides all seemed happy to leave Washington for a bit - and what better place to go than Paris.