Jan. 9 (UPI) -- The Department of Defense released a timeline Friday detailing its planning and response leading up to Wednesday's riot in the Capitol Building.
According to the timeline, city leaders first requested help from the Washington, D.C. National Guard on Dec. 31, but U.S. Capitol Police declined assistance from the Pentagon twice in the days before the event.
But the USCP did request assistance from the Pentagon shortly before 2 p.m., after rioters had breached the Capitol.
Once they did, it took several hours -- until shortly before 6 p.m. -- before Guard troops arrived.
According to the Pentagon's timeline, the intervening hours were consumed with phone calls and meetings between city, military and Congressional leaders to discuss which forces to send and how to equip them.
Washington, D.C. Mayor Muriel Bowser's office told NBC that Army Secretary Ryan McCarthy was responsible for the delay, as well as several other key decisions related to the National Guard's response.
They included decisions to cap the number of activated National Guard troops at 300 and not to use armored vehicles.
Bowser's spokeswoman also said McCarthy directed Guard members were "not to move East of 9th Street NW," which is about nine blocks west of the Capitol Building.
According to the Pentagon, the military agreed to provide 340 members of the D.C. National guard to the D.C. Metropolitan Police Department.
Trump supporters are planning to return to Washington later this month for the inauguration of President-elect Joe Biden.
McCarthy is currently reviewing whether Guardsmen should be armed for the inauguration with lethal or nonlethal weapons.