France has destroyed an Islamic State (IS) logistics depot in its first airstrikes against the militant group in Iraq.
President Francois Hollande said Rafale fighter jets, accompanied by support planes, "entirely destroyed" the depot in the north of the country.
Iraq's military spokesman said four morning airstrikes killed dozens of fighters.
"Other operations will follow in the coming days with the same goal - to weaken this terrorist organisation and come to the aid of the Iraqi authorities," Mr Hollande said. "There are always risks in taking up a responsibility. I reduced the risks to a minimum."
Zumar and surrounding towns are heavily contested by IS fighters, even though Iraqi and Kurdish security forces have managed to make headway nearby with the support of US airstrikes.
France is the first foreign country to publicly add military muscle to American airstrikes against IS.
Mr Hollande has ruled out French troops on the ground.
US Central Command said on Thursday that the US military has conducted 176 airstrikes in Iraq since August 8.
On Wednesday, it hit a militant training camp southeast of Mosul and an ammunition stockpile southeast of Baghdad. It has also conducted a number of strikes this week in Iraq's Anbar province, near the strategic Haditha Dam.
The two men visited an American military cemetery in Normandy.
Gen Dempsey, who was told of the attack by de Villiers, praised the French action.
"The French were our very first ally and they are there again for us," he told reporters travelling with him in Normandy. "It just reminds me why these relationships really matter."