One of the most senior cabinet officials in the Trump administration, Acting Secretary of Defense Chris Miller, has told VICE on Showtime that he believes the speech made by former President Donald Trump on the morning of Jan. 6 was responsible for causing a mob to violently attack the Capitol later that day.

Trump installed Miller after firing his predecessor Mark Esper in the days following the election. Speaking exclusively to VICE on Showtime, Miller said “would anybody have marched on the Capitol, and tried to overrun the Capitol, without the President’s speech? I think it’s pretty much definitive that wouldn’t have happened.”

“This is a criminal enterprise,” Trump told the crowd on Jan. 6, referring to the election. “And we fight. We fight like hell. If you don’t fight like hell, you’re not going to have a country anymore.” Hours later, members of the same crowd were rampaging through Congress to stop lawmakers from certifying the results.

Recalling the events of Jan. 6, Miller said that he wasn’t sure whether or not former President Trump was aware that his speech might have such extreme consequences, but he was certain the attack would not have happened without them. Listening to the remarks that morning, he said he found some of the comments “concerning” and that they set alarm bells ringing.

“It seems cause and effect,” Miller said, referring to Trump’s speech and the deadly riot that left five people dead. “The question is, did he know he was enraging people to do that? I don’t know.”

As acting secretary of defense on that day, Miller was ultimately in charge of the military’s response. His comments are significant in that they tie directly to the incitement of insurrection charge that former President Trump was acquitted of at his second impeachment trial in February.

Miller was criticized for his part in the response to the Capitol attack, with some faulting the Department of Defense for the time it took to deploy the National Guard. Miller released a statement on Jan. 15 announcing a Department of Defense investigation, and Pentagon officials at the time rejected any blame for having not deployed reinforcement from the national guard while rioters overran the Capitol Police and ransacked the Capitol..

Miller rejected the criticism and said the speed of response was normal by military standards. “It comes back to understanding how the military works—this isn’t a video game, it’s not Black Ops Call of Duty,” Miller said. But the response is currently under intense scrutiny, with Senate committees examining the timeline of decisions taken by Trump administration officials.

Miller’s appointment on Nov. 9 raised eyebrows in the national security establishment, with many seeing the move as a Trump administration attempt to politicize the Pentagon after losing the election. On Jan. 3, all ten living former Secretaries of Defense published an open letter warning Miller and his team that there must be a peaceful transition of power.

But Miller rejected the notion that was any intent to use the military for unconstitutional means. “There was a lot of concern that we were just some sort of Trump hatchet men coming in to do heinous things to the Department of Defense, which couldn’t be further from the truth.”

Still, Miller described the political climate at the time as a “constant drumbeat” of “potential illegal, immoral and unethical activities” that made him closely examine his “ethical, moral and legal red lines.” Miller said he made a plan that he would step down rather than carry out an order he was uncomfortable with.

“I knew that I was not going to cross any of those lines and, if asked, I would resign,” Miller said. “If it’s antithetical to the Constitution or the Uniform Code of Military Justice it’s an illegal order and you don’t follow it.”

Miller’s comments are part of an exclusive glimpse into political maneuverings at the Pentagon during the final weeks of the Trump administration, based on interviews with Trump officials and additional reporting from Vanity Fair‘s Adam Ciralsky who gained exclusive access to Miller and his team in the waning days of the administration.

The story will air exclusively on VICE on Showtime at 8 p.m. on Sunday March 14