Many of the House Republicans who on Wednesday stormed a closed-door hearing that was part of the impeachment inquiry into President Donald Trump would have been allowed to go inside if they wanted.

More than 30 Republicans forced their way into the hearing, delaying it for about five hours. They now face allegations of risking national security.

Twelve were already able to attend the hearing, as they sit on relevant committees, but they said they entered to protest its secrecy.

Longstanding rules say witnesses should be interviewed in a classified setting. House Democrats have said they will hold open hearings once their initial investigation is done.

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Twelve House Republicans who stormed a closed-door impeachment hearing in protest on Wednesday already had permission to attend.

More than 30 House Republicans headed by Rep. Matt Gaetz forced their way into the hearing, delaying it for about five hours. They said in a press conference that they were protesting the secrecy of the hearing and would not leave until it was made public.

They did not address the allegations against President Donald Trump in the impeachment inquiry, which centers on his request to Ukraine's president to investigate Joe Biden, the former vice president and a 2020 Democratic challenger to Trump.

But as Business Insider's Kelly McLaughlin highlighted, there are longstanding rules that witnesses are supposed to be interviewed in a way that can stay classified.

Axios and BuzzFeed News reported that 12 of those Republicans were actually already able to attend the hearing because they sit on relevant committees, including the Oversight or Foreign Affairs committee:

Paul Gosar of Arizona

Mark Green of Tennessee

Jody Hice of Georgia

Jim Jordan of Ohio

Fred Keller of Pennsylvania

Carol Miller of West Virginia

Ralph Norman of South Carolina

Mark Meadows of North Carolina

Scott Perry of Pennsylvania

Steve Watkins of Kansas

Ron Wright of Texas

Lee Zeldin of New York

A representative for Keller told BuzzFeed News that he attended to protest "in solidarity with those members of Congress who are not allowed in the hearings, to review testimony, or read transcripts of this secret inquiry."

A representative for Rep. Ken Buck, who's on the Foreign Affairs Committee and was listed as a lawmaker who planned to attend, told BuzzFeed News that Buck did not attend but tweeted criticism of the closed testimony.

The Republicans entered the room, known as a Sensitive Compartmented Information Facility, during the testimony of Laura Cooper, the deputy assistant secretary of defense for Russia, Ukraine, and Eurasia.

Read more: Intelligence veterans say Republicans storming a secure congressional facility was a 'thuggish' and 'offensive' stunt that risked national security

Intelligence veterans who spoke with Business Insider's Sonam Sheth and Lauren Frias said the lawmakers could have jeopardized national security by entering a SCIF.

Rep. Matt Gaetz in February. Alex Wong/Getty Images

A SCIF is "designed to prevent electronic eavesdropping" from foreign intelligence services, a former top House Intelligence Committee staffer said, and no electronic devices are allowed in. But witnesses told The Washington Post that several of the Republicans brought their phones.

Glenn Carle, a former CIA covert operative, told Business Insider that phones in such a context were "essentially microphones for sophisticated intelligence services."

Democrats have said they will open up public hearings in the coming weeks, after their initial investigation.