Questions remain about whether a leader of the Khorasan group was killed in a U.S. airstrike last week in Syria.

White House deputy national security adviser Tony Blinken said on "Fox News Sunday" that the administration has not yet confirmed Fadli's death, which was reported by an al Qaeda-linked Twitter account.

"We want to make sure that he's not trying to, in effect, fake his death and go underground. But there are serious indicators that he was removed," said Blinken, who also misidentified Fadli as a "significant leader of the ISIL effort."

Catherine Herridge reported on "America's Newsroom" this morning that the National Security Council tells Fox News that Blinken misspoke and that Fadli is not part of the Islamic State.

Fadli is said to have been a close associate of Usama bin Laden and is believed to have known about the 9/11 attacks in advance.

There are also new questions about the Khorasan group, which one terrorism expert writes "does not exist." Andy McCarthy argues in National Review that Khorasan is a "fictitious" group created by the White House to justify strikes on Syria without approval by Congress.

The White House said the Khorasan group was in the final stages of planning an attack and posed an "imminent threat" to the United States.

McCarthy argues in his piece that the Obama administration is going out of its way to avoid calling terror groups "al Qaeda."

Watch Chris Wallace's full sit-down with Blinken below: