The pleasantries, lack of handshake between Trump and Merkel notwithstanding, are officially over.

One day after Trump returned to his favorite medium to slam Germany for abusing NATO’s funding scheme, and US defense spending generosity, accusing Germany of owing “vast sums” of money to both NATO and the US, Germany has struck back. As a reminder, this is what Trump tweeted on Saturday morning:

Despite what you have heard from the FAKE NEWS, I had a GREAT meeting with German Chancellor Angela Merkel. Nevertheless, Germany owes vast sums of money to NATO & the United States must be paid more for the powerful, and very expensive, defense it provides to Germany!

That in turn, was followed on Sunday morning by a statement by German Defense Minister Ursula von der Leyen in which she responded to Trump, rejecting the US president’s claim: “There is no debit account at NATO,” von der Leyen said in a statement, adding that it was wrong to link the alliance’s target for members to spend 2 percent of their economic output on defense by 2024 solely to NATO.

“Defense spending also goes into UN peacekeeping missions, into our European missions and into our contribution to the fight against IS terrorism,” von der Leyen said. The defense minister added that everyone wanted the burden to be shared fairly and for that to happen it was necessary to have a “modern security concept” that included a modern NATO but also a European defense union and investment in the United Nations.

Before taking office, Trump suggested that the U.S. might not come to the defense of allies who didn’t meet the 2 percent spending goal, and said the coalition doesn’t always best serve American interests. But U.S. officials have publicly praised the alliance since Trump took office, and Merkel is among European leaders who have outlined steps to boost defense spending to the target level.

To be sure, Trump wasn’t the first U.S. leader to complain that most NATO nations, including Germany, weren’t meeting the alliance’s goal that members spend 2 percent of their GDP on defense. Germany spends about 1.2% currently.

In fact, none other than President Barack Obama in 2016 said in an interview with The Atlantic about his foreign policy doctrine that “free riders aggravate me.” Sigmar Gabriel, Germany’s foreign minister, said a few weeks ago said that meeting the 2 percent goal is “unrealistic,” although that’s a much lower percentage than the U.S. spends on defense.

The exchange of barbs took place shortly after Friday’s visit by Merkel, postponed from earlier in the week by a snowstorm, which was a day of tense cordiality and sometimes awkward body language. Trump was unresponsive when Merkel leaned in for a handshake in the Oval Office at the request of photographers. There were few public attempts at the jocularity leaders often use to leaven such encounters, except for a barbed reference Trump made that they had “in common, perhaps” the experience of surveillance by U.S. intelligence.

As Bloomberg adds, the visit was a test of Trump’s foreign policy vision and represented Trump’s first face-to-face talks with a veteran German leader whom he frequently maligned on the campaign trail, and whose free-trade, open-border politics stand in marked contrast to Trump’s nationalistic rhetoric. “He’s been president less than two months; she has been chancellor more than 10 years,” said Richard Haass, president of the Council on Foreign Relations. “She has all this experience. She’s the most important leader in Europe. Some would say she’s the most important leader in the world right now.”

Trump was infuriated at a German reporter’s question about his accusations that Obama had placed him under surveillance before jokingly referning a disclosure that emerged as a result of the Snowden revelations that president Obama was intercepting Merkel’s mobile phone communications. Turning to Merkel, he joked, “At least we both have something in common, perhaps.”

Merkel didn’t smile.

Merkel has been looking to Trump to ease concerns within Europe that the U.S. could abandon efforts to pressure Moscow into changing course. So far it remains unclear just what Trump’s latest diplomatic track is vis-a-vis the Kremlin following a media barrage that his aides have had undisclosed relations with Russia. This week there is a hearing on Russian “hacking” of the US elections, where Trump’s ties to Moscow will be a prominent fixture of discussion.

The Emergency Election Sale is now live! Get 30% to 60% off our most popular products today!