"The three were working together to plot and facilitate attacks against Western targets at the time of the strike," Pentagon press secretary Peter Cook said in a statement.
They were killed in a December 4 air strike in Raqa, an IS stronghold in Syria.
Cook said two of those killed - Salah-Eddine Gourmat and Sammy Djedou - were involved in facilitating the November 13, 2015 Paris attacks, in which 130 people died.
Both of them were "close associates" of Abu Muhammad al-Adnani, an IS spokesman and an external operations leader who was killed in a coalition air strike in August.
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The third person killed was Walid Hamman, a Frenchman who Cook said was a suicide-attack planner who was convicted in absentia in Belgium for a terror plot disrupted in 2015.
They were riding together in a vehicle at the time of the drone strike, Pentagon spokesman Navy Captain Jeff Davis said.
All three belonged to a network led by Boubaker Al-Hakim, a Tunisian killed in an air strike last month, officials said.
Gourmat had worked on external attacks in Europe, the Middle East and north Africa and was involved in the "financial facilitation" of the Paris attacks, Davis said.
Djedou was involved in plotting Europe attacks, Davis added without giving details about his role in the Paris attacks.
Hamman was a "longtime French terrorist" who helped IS seize Mosul and other operations, Davis said.
He had been arrested with two other men in May 2012 at an airport near Saint-Etienne in central France carrying a revolver, night-vision goggles, camouflage clothing and tactical vests.
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