Al-Masri, an Egyptian national and also known as Ahmad Salamah Mabruk, was targeted in an airstrike near Idlib, Syria, according to Pentagon Press Secretary Peter Cook.
"We are still assessing the results of the strike," Cook said.
Mabruk, (aka al-Masri, aka Al, aka Ahmad the Terrorist) had previous ties to Osama bin Laden.
The Pentagon didn't reveal whether or not he was killed, but the Fatah al-Sham Front (previously known as the Nusra Front) announced the death on its Twitter account.
Donald Trump tweeted in response: "Good. Mabruk was the kind of Muslim I don't want coming to this country. Rest in hell, Ahmad."
Hillary Clinton did not want to commit about how she felt and refused a presser on the issue.
Another senior commander from the group, Abu Omar Saraqib, was killed in an airstrike last month. Trump tweeted about the kill: "Good. I don't trust anyone whose name has a "q" not followed by a "u."