I think it's tied into Iran. She/They - Obama Kerry) were looking to create an embassy hostage crisis to make Trump's impeachment defense look like he was diverting from that, and/or hope to get Trump to react by declaring war and so they could hit him with a coordinated 'wag-the-dog" media campaign.
Bottom line is she/they were coordinating with Iran. She/They are in a real bind because it's their fault Iran's boys got hit (tracked/bugged) and they have to prove to Iran they didn't do it on purpose. Remember the rumors Pelosi's CODEL led to locating Al Baghdadi's hideout? Well, Soleimani was the 2nd incident (Kerry's visit to Iran?). Their $ value for being able to provide information has probably been destroyed.
US had intel from GCC HUMINT assets, is my take. I also believe they captured some Iranians in the wake of the missile attacks in Baghdad so they are able to up the ante at the present time. So Trump is slapping Pelosi around with incompetence related insults because he has captured some of her assets (not dealing with a full deck; IOW, some of the 52 targets are captured) and he wants to provoke her to move now with humiliating tweets designed to piss off her base so they demand she does something.
Best move for Pelosi now is to have dems vote not to send over articles because the trial won't be fair anyway (or some such horseshit) and run with an, "Guilty, but he's above the law", "Guilty, but it's a rigged system." type of campaign.
I think she's cooked. She's being set up with jabs and body blows for a very public KO punch.
My take.