But the U.S. hasn't made the "official call" yet, the sources said.

A Twitter account that purportedly belongs to Sanafi al Nasr, a senior figure in al Qaeda in Syria, announced Drugeon's death in a coalition airstrike in the countryside west of Aleppo, Syria, CNN Terror Analyst Paul Cruickshank reported. In eulogizing Drugeon, al Nasr mentioned an airstrike late last year that injured Drugeon.

"It's a big get," Cruickshank said. "Drugeon was a skilled bombmaker who had access to a lot of Europeans and Westerners who could be equipped with a device to potentially target Western passenger jets."

It's unclear whether the strike that killed Drugeon was specifically targeting him or whether it was a so-called signature strike, called in based on a pattern of activity.

The French Foreign Ministry declined to comment.