Earlier quoted context omitted.
When it happened, there was a reporter on CBC talking about how it was common knowledge in DC for a long time that there was a protest planned there. So indeed. The real question is why was there seemingly no preparation to handle it.
Compared to other DC protests, the absence of preparation was the preparation. Clearly some of the Establishment wanted it to succeed.
It's hard to overstate how poorly they managed this. This is something a special investigation should be commissioned out by congress/the DOJ.
[1] https://www.npr.org/2020/06/01/867532070/trumps-unannounced-...