During his ceremonial exit from Paris, Trump shook the hand of French President Emmanuel Macron for approximately 25 seconds, coupling it with a double-handshake combo with France's first lady, Brigitte Macron, whom the president also hugged and kissed while maintaining his five-finger embrace of President Macron.
Tributes have been flooding in to the 86 lives lost on Twitter.
The event has featured a flypast of fighter jets to symbolise present-day military co-operation between France and America.
United States troops dressed in the brown uniform and gaiters of the Great War were among 3,720 soldiers in the parade.
Macron paid homage to the solidarity of the French people in the face of the attack and said: "We forgot the name of this murderous anonymous [the terrorist] but we remember the names" of those killed.
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- Macron started his own political movement just over a year ago.
Yannick Mireur, a French political scientist, said Macron went into the meeting with "a rather rare quality - that of empathy, interest in the person to try and understand him, to find the key to him". IS claimed responsibility for that attack and others in France.
Earlier, the French leader elected in May bestowed awards, including the coveted Legion of Honour, on emergency workers and police who responded to the carnage.
"Something could happen with respect to the Paris accord", Trump said, six weeks after announcing that the United States would abandon the 2015 pact.
Several highlights of the parade put the United States in the spotlight. His protectionist stance on trade has also set him adrift.
Trump made the comments to Macron during a visit to Les Invalides museum in Paris on Thursday, where the tomb of Napoleon is held.