Trump and Macron were once so close that their friendship was regarded as a "bromance".
Mr Trump jokingly offered them to France, saying: "Would you like some nice [IS] fighters?"
"I'm hearing the report is very powerful, but I'm hearing that by reading lots of different things, not from inside information", said Trump, who predicted there will be "a lot of devastating things in that report".
Ahead of the summit, Turkish president Recep Tayyip Erdogan warned that he would veto a plan to defend Poland, Lithuania, Latvia, and Estonia from Russian aggression unless the alliance recognised the Kurdish YPG militia, who Turkey is fighting in Syria, as terrorists.
"I like Turkey and I get along very well with the President".
Sitting next to Trump, Trudeau said he thinks the relationship between Canada and the United States has never been stronger, and refused to bite on a reporter's question about whether he's threatened to abandon the trade agreement. "Before me, the United States was a sucker", Trump added.
Macron said that he saw a waning commitment to the transatlantic alliance by the main guarantor of stability in Europe - the United States - citing Washington's failure to consult the allies before pulling forces out of northern Syria in October.
"We find a tremendous security problem, with respect to Huawei", the president said. "What we don't do traditionally as loving allies and friends, what we don't do traditionally, is get involved in each other's election campaigns", Johnson told LBC radio.
Trump has gone from labeling the agreement "obsolete" and earlier this year privately mulling a USA withdrawal from the alliance, to outright praising the 29-country alliance.
"He just had the idea - Emmanuel had an idea: let's tax those companies", Trump said during a meeting with Stoltenberg.
The US President responded in kind in London, having arrived for a summit about the 70-year-old military alliance.
The United States has threatened to impose duties of up to 100 per cent on imports of champagne, handbags and other French products worth US$2.4 billion (S$3.3 billion) after a U.S. government investigation found that France's new digital services tax would harm USA technology companies.
Later Tuesday, Trump is expected to have tea with Prince Charles and attend two receptions - one hosted by Queen Elizabeth II and later, another hosted by British Prime Minister Boris Johnson. "I'm looking at him and I'm saying he needs protection more than anybody and I see him breaking off, so I'm a little surprised at that", Trump added.
Oil prices gain as investors eye deeper OPEC cuts
USA crude oil inventories likely declined by 1.8 million barrels last week, according to six analysts polled by Reuters. West Texas Intermediate (WTI) futures rose 91 cents, or 1.7%, to $56.08 a barrel, having risen by more than $1 earlier.
Health Ministry confirms 24 influenza deaths to date
This can include your health care provider's office, county health departments, pharmacies, and community vaccination clinics. It is estimated that on average about 8% of the USA population gets sick from the flu each season (2018 CDC study).