Sixteen years after the worst terrorist attack in history hit the United States, President Donald Trump and his administration failed to mention the terms “radical Islam” or “Islamic terrorism” during a ceremony in Washington D.C.

In fact, not only did President Trump fail to use those words, but neither did Vice President Mike Pence, Defense Secretary James Mattis, Acting Homeland Security Secretary Elaine Duke, nor Attorney General Jess Sessions.

Speaking at the Pentagon, President Trump danced around using the terms. Instead he referred to the Islamic terrorists as “horrible, horrible enemies,” “barbaric forces of evil and destruction,” “terrorists who attacked us,” and “enemies of all civilized people.”

President Trump’s decision to eschew mentioning the role that Islam played in 9/11 is especially shocking when considering some of his prior tweets on Islam:

Mattis also downplayed the role that Islam played in 9/11 by referring to the Islamic terrorists as “maniacs disguised in false religious garb.”

Sessions came very close to calling out Islamic terrorism by referring to them as “extremists,” but did not refer to any specific ideology or religion. “For these extremists, it’s more than religion; it’s ideology,” he said. “We have no choice but to defend against it.”

Pence did mention ISIS while speaking at a memorial in Pennsylvania for flight 93 but failed to use the words “radical Islam” or “Islamic terrorism” when speaking of the 9/11 attacks.

Acting Department of Homeland Security (DHS) Secretary Elaine Duke issued a statement in remembrance of 9/11 which also failed to use the terms.

One possible explanation for the Trump administration failing to mention Islam on 9/11 is the influence that national security adviser H.R. McMaster has over the administration.

Earlier this year, CNN reported that McMaster said in a National Security Council meeting that using the term “radical Islamic terrorism,” is not helpful in defeating terrorist groups – a nearly identical belief to the position held by the Obama administration.