The Pentagon said Abu Hani al-Masri, the Qaeda veteran, was one of those killed in the precision airstrikes near Idlib carried out on February 3-4.
Al-Masri was an early official in al-Qaeda, overseeing the group's training camps in Afghanistan in the 1980s and 1990s as he worked with Qaeda founder Osama bin Laden and current leader Ayman al-Zawahiri.
There "he recruited, indoctrinated, trained and equipped thousands of terrorists who subsequently spread throughout the region and the world," the Pentagon said yesterday in a statement.
"These strikes disrupt al-Qaeda's ability to plot and direct external attacks targeting the US and our interests worldwide," said Pentagon spokesman Jeff Davis.
The US has mostly focused its attacks in Syria on the Islamic State group. But in recent months, US forces have also launched several attacks against its al-Qaeda rivals.
Idlib province is largely occupied by the former Syrian branch of al-Qaeda, Fateh al-Sham, which has been allied to several Syrian rebel groups fighting the government.