Trump also lashed out at France for a French digital service tax that he said unfairly discriminates against United States tech companies, including Google, Apple, Facebook and Amazon. He called it a "great process" between the countries to see the deal become a reality. Trump said he is weighing issuing sanctions against Ankara if they move forward with plans to buy the weapons.
"It is true you have foreign fighters coming from Europe, but this is a tiny minority of the overall problem", French. "France is not doing well economically at all", he said hours before he will meet one-on-one with the French leader. "This is our number one priority and it's not yet done", he said.
For the third summit in a row, Trump is expected to renew demands that European allies and Canada step up defense spending.
In London at a bilateral meeting alongside NATO Secretary-General Jens Stoltenberg, Trump reacted to Macron telling The Economist magazine in early November that recent US troop actions in Syria are contributing to the "brain death" of the NATO military alliance.
In sign of what's to come, Turkish President Recep Tayyip Erdogan said that he would oppose a plan to defend Baltic countries unless North Atlantic Treaty Organisation labels the Syrian Kurdish People's Protection Units (YPG) as terrorists.
"I do think the big report to wait for is going to be the Durham report", he said. "You can take every one you want".
Mr Trump and Mr Macron have had an patchy relationship in the almost three years since the former reality TV star became Commander in Chief.
"He wants to make sure future generations have climate that is good climate as opposed to a disaster, and I agree".
Trump was only the third U.S. president to receive an invitation for a State Visit from Her Majesty, after George W Bush and Barack Obama.
That threat raises new questions about NATO's commitment to its collective defense clause - Article 5 - under which all allies vow to come to the aid of a member under attack.
Preparations for the two-day meeting have been overshadowed by a raucous debate over defense spending, policies concerning Syria, and a bitter dispute between France and Turkey.
He told The Sun tabloid that Britain's intelligence allies - including the United States - were "very anxious" about working with a Corbyn-led government.
Democrats have been looking into Trump's efforts to pressure Ukraine to investigate political rival Joe Biden, the former USA vice president who is seeking the Democratic nomination to face Trump in the 2020 election, and his son Hunter Biden, who was a board member of a Ukrainian energy company.