They're there because Biden has been having meetings in secret with Chinese officials and the Chinese know you don't negotiate the destruction of a country within its borders without military protection, and they're there because Biden goes to bed by 2pm and doesn't want anyone to find out how little he's actually awake in a day, and they're there to protect Hunter in case some heroes in a law enforcement body decides to try to arrest him, and they're there because Biden is a dictator who is afraid of being overthrown. The Whitehouse will have a permanent military force now, guaranteed. They'll just hide them better and pretend like the whole place isn't an occupation by an illegitimate president.