"President Macron of France has just suggested that Europe build its own military in order to protect itself from the U.S., China and Russia. Very insulting, but perhaps Europe should first pay its fair share of NATO, which the U.S. subsidizes greatly," Trump tweeted minutes after landing in France. He is set to spend the weekend in Paris to commemorate the centennial of the end of World War I.
Tuesday on Europe 1 radio, Macron called for a "real European army" within the European Union, according to AFP.
"We have to protect ourselves with respect to China, Russia and even the United States of America," Macron said.
Macron also suggested that since the start of Trump's presidency, the US has been seen as a less reliable ally.
"When I see President Trump announcing that he's quitting a major disarmament treaty which was formed after the 1980s euro-missile crisis that hit Europe, who is the main victim? Europe and its security," he said.
Macron has been advocating a similar position for months.
A senior French official said Friday night that Trump took Macron's words out "out of context."
According to the official, Macron will likely want to respond to Trump's tweet directly himself, and likely Saturday.
The official, though, clarified the language Macron used, saying that the French leader did not mean he wanted a European army but better coordination and funding of Europe's already-existing resources.
The official said that Macron was conveying that Europe should organize better to protect itself. There is already a European defense project, and Macron would like to see more capability, the official said.
"Not a European army. He did not mean Europe should form an army," the official said. "And this is all complementary to NATO, not separate from it."
Further strain in Trump-Macron relationship
Trump's tweet on Friday could preview another high-level international meeting in which the US President distances himself from traditional American allies. Unlike the tense G7 summit in June, however, Russian President Vladimir Putin will be present at this weekend's commemoration.
While both Trump and Macron appeared to be off to a warm start following Trump's inauguration, their relationship appears to have soured.
During a call about trade and migration in June, sources familiar with the call told CNN that it didn't end well.
"Just bad. It was terrible," a source told CNN. "Macron thought he would be able to speak his mind, based on the relationship. But Trump can't handle being criticized like that."
And more recently, a senior diplomatic source told CNN that Trump was "ranting and venting on trade" with Macron during their bilateral meeting in September.
There was "some rapport" between the two, "but it's not what it (once) was," the source said.
Macron isn't the only European leader to raise the prospect of Europe doing more for its own defense.
EU President Donald Tusk made a similar suggestion in May after Trump had pulled out of the Iran deal and the Paris climate agreement, threatened a series of trade disputes with Europe and constantly criticized NATO.
"Europe must do everything in its power to protect, in spite of today's mood, the transatlantic bond. But at the same time we must be prepared for those scenarios, where we will have to act on our own," Tusk said.
Tusk also said that the EU "should be grateful" to Trump "because, thanks to him, we have got rid of all illusions."
"Looking at the latest decisions of President Trump, someone could even think: With friends like that, who needs enemies?" Tusk said, later adding, "He has made us realize that if you need a helping hand, you will find one at the end of your arm."
Trump's tweet on Friday continues his oft-repeated misunderstanding of the way NATO works. The President has consistently complained that NATO members don't adequately contribute to the shared defense agreement, suggesting the other 28 members somehow owe the US money. Actually, all alliance members commit to spending 2% of their GDP on defense. While few have reached that threshold, most members have increased spending in recent years and are nearing the suggested level of spending.
CNN's Nicole Gaouette, Jennifer Hansler, Kaitlan Collins and Veronica Stracqualursi contributed to this report.