Maj. Gen. William J. Walker testified that he did not receive permission to deploy troops for hours on Jan. 6, as violence by pro-Trump supporters escalated.
In his final days in office before a new administration takes over, Army Secretary Ryan McCarthy changed a regulation to sidestep court rulings requiring the medical examination.
The troops will be the National Guard and not active-duty. But officials know such events are fraught with risk and cite Kent State in 1970, Tiananmen Square in 1989 and Tehran in 2009.
The armed National Guard troops will be responsible for security around the Capitol building complex, officials said. About 15,000 Guard troops are expected to be deployed in the city.
Army Secretary Ryan D. McCarthy asked those leading the inquiry to examine whether commanders at the Texas base allowed a climate of harassment to spread.
The address comes as the coronavirus spreads — and during a breakdown in relations between the president and the nation’s top military leaders.
“My Administration will not even consider the renaming of these Magnificent and Fabled Military Installations,” President Trump tweeted Wednesday.