If you’re ever confused about why the US government is doing something, the answer is probably to preserve and extend the US empire. From Caitlin Johnstone at medium.com:

Former MSNBC host Krystal Ball slammed her ex-employer’s relentless promotion of the Russiagate conspiracy theory following the embarrassing spectacle of Robert Mueller’s hearing before the House Judiciary and Intelligence Committees on Wednesday.
“After watching seven hours of a spectacle that felt much more cruel than enlightening, I cannot avoid pondering a question which honestly gives me no joy to ponder: just how much damage has MSNBC in particular done to the left?” The Hill’s Rising star began, before excoriating her former employer’s “fevered speculations” about an “Infowars conspiracy theory” and the way it hosted people like Jonathan “maybe Trump has been a Russian asset since the 1980s” Chait and “conspiracy gadfly Louise Mensch” in search of ratings bumps.
“This whole setup has done more damage to the Democrats’ chances of winning back the White House than anything that Trump could ever have dreamed up,” Ball argued. “Think about all the time and the journalistic resources that could have been dedicated to stories that, I don’t know, that a broad swath of people might actually care about? Healthcare, wages, the teachers’ movement, whether we’re going to war with Iran? I’m just spitballing here. I actually heard some pundit on Chris Hayes last night opine that independent women in middle America were going to be swayed by what Mueller said yesterday. Are you kidding me? This is almost as bonkers and lacking in factual basis as that time Mimi Rocah said that Bernie Sanders is not pro-women because that was what her feelings told her. Rocah, by the way, a political prosecutor with no political background, is only opining at MSNBC because of her role in leading viewers to believe that any day now SDNY is going to bring down Trump and his entire family.”