These jabs come just weeks after the G7 summit and subsequent worldwide flaps over tariffs and the President's trade wars, and just ahead of Trump's upcoming one-on-one with Vladimir Putin.
"Many of us are concerned - I certainly am - about the president's ongoing rhetoric that really demeans or ridicules our allies and praises our adversaries", Flake said.
European Council President Donald Tusk directed a message at Trump, saying "it is always worth knowing who is your strategic friend and who is your strategic problem".
According to the German newspaper Frankfurter Allgemeine Zeitung, as the latest tax estimate predicts much higher government revenues than expected, Scholz promised more money to the army, succumbing to pressure from German Defense Minister Ursula von der Leyen, a member of Angela Merkel's Christian Democratic Union.
Along with trade policies, Trump has been demanding that North Atlantic Treaty Organisation members increase their defense spending to come into line with a 2014 commitment while complaining that Europe benefits more from the partnership than the United States.
Anticipation Builds Ahead Of Trump's Supreme Court Nominee Unveiling
Jon Kyl will guide President Donald Trump's Supreme Court nominee through the Senate confirmation process. Chellie Pingree (D): " Brett Kavanaugh is a far-right choice to sit on our nation's highest court".
"Getting ready to leave for Europe". We're being taken advantage of by the European Union. "Charge us big Tariffs (& Barriers)!" he wrote on Twitter. "This is not fair, nor is it acceptable".
"It will become increasingly hard to justify to American citizens why some countries continue to fail to meet our shared collective security commitments", Trump said in a letter addressed to Norwegian Prime Minister Erna Solberg seen by Bloomberg News.
"I think that getting along with Russian Federation, getting along with China, getting along with others is a good thing, not a bad thing", he said. In the past few weeks, Trump has sent sharply worded letters to the leaders of several European countries, including Germany, Italy and Norway, and also to Canada, warning that the USA was losing patience.
A CNN panel on Tuesday was appalled by President Donald Trump's declaration that it would be "easier" for him to meet with Russian President Vladimir Putin than it would be to meet with traditional American allies such as the United Kingdom on his upcoming foreign trip.
Diplomats fear an acrimonious meeting could undermine efforts to show unity in the face of the growing threat on the alliance's eastern flank - particularly with Trump set to meet Putin in Helsinki a few days later. "Frankly, Putin may be the easiest of them all".