"Germany is a captive of Russia because it is getting so much of its energy from Russia", Trump said, taking particular aim at the proposed Nord Stream II gas pipeline, which he has previously criticised.
"So we're protecting Germany, we're protecting France, we're protecting all of these countries and then numerous of these countries go out and make a pipeline deal with Russia where they're paying billions of dollars into the coffers of Russia", Trump said.
Germany has come under pressure from the United States to halt the Nord Stream 2 oil pipeline which will run through the Baltic Sea to Germany and extend Russian influence over energy supply...
Instead of blaming Putin for invading Ukraine - an act of war that prompted the G7 to expel Russian Federation from the group - Trump has attempted to pin blame on former President Obama.
The EU president then directly addressed Trump, "who for a long time now has been criticizing Europe nearly daily for, in his view, insufficient contributions to the common defense capabilities, and for living off the United States".
"We have to talk about the billions and billions of dollars that's being paid to the country we're supposed to be protecting you against", Trump said, referring to European purchases of Russian natural gas.
America's North Atlantic Treaty Organisation partners will expand military outlays by a combined 3.82 percent in 2018, bringing the cumulative rise since the start of 2015 to more than $87 billion, according to the alliance, which Trump is due to visit for a two-day summit starting Wednesday.
Stoltenberg said he expected a "open and frank" debate about defence spending at the summit but tried to play down the differences opening up between allies.
Trump made the comment while addressing reporters before he and First Lady Melania Trump boarded presidential helicopter Marine One.
The 29 allies are due to restate a commitment to try to spend two percent of GDP on defense by 2024, according to excerpts of their final summit declaration seen by AFP.
Both countries will be well-served in the meantime by the British parliament's recent decision to ratify the deal, known as CETA, said Joseph Pickerill, a spokesman for International Trade Minister Francois-Philippe Champagne.
German defence minister Ursula von der Leyen also responded defiantly to Mr Trump's barb.
While Mr Trump is looking to improve relations with Russian Federation, there has been alarm at the deteriorating climate with his allies in Europe and what he might agree to with President Putin.
Despite Russia's aggressive moves in Ukraine and confirmed election meddling in the US, the president wouldn't say if Putin was friend or foe.
He even suggested his meeting with Putin on Monday would the "easiest" of his trip in Europe.
Trump complimented Stoltenberg, saying "he's worked very hard on this problem". "Who would think", the president said.
The trade office's figures say U.S. imports from the European Union rang in at $592bn- leaving a $91bn goods and services trade deficit.
"Dear America, appreciate your allies, after all you don't have that many", Tusk said, before reminding Trump that European troops had fought alongside Americans in Afghanistan following the September 11, 2001 attacks on the United States.
The 1.5 percent level forecast for NATO's European members in 2018 compares to 1.46 percent past year, 1.44 percent in 2016 and 1.42 percent in 2015.