He's not demolishing and reconstructing just to leave after 3 years. Saying this as an immigrant who lived under full on military, and pseudo-autocratic democratic rulers.
That's exactly what the East Wing already was. "...rebuilt in 1942 during the Franklin Roosevelt administration to create more office space and provide cover for a bunker during World War II."
a non critical void space, provides a red herring for penetrating munitions, before they hit actual bunker structure.
germany was doing this with uboat gantries, and munitions factories back in the 40's
During 911, the President who was not in Washington at the time was flown to a nuclear bunker:
https://www.wowt.com/2021/09/08/20-years-after-911-look-insi...