Thread by @dsamuelsohn

NEW: The Trump administration failed to follow a well-known playbook for coordinating police and law enforcement responses ahead of the deadly pro-Trump riots at the US Capitol this week, national security experts told @Politicsinsider - by @rbravender ($) ow.ly/Up4f50D3NRH

It's a framework government officials regularly use for big events that pose major threats to national security, like a State of the Union address, the Olympics, or the Super Bowl.

Those events are officially known as National Special Security Events, and they usually happen a few times per year for significant occasions. Getting an NSSE designation means top law enforcement officials get in a room together to address threats and respond in real time.

But the Trump-led Department of Homeland Security didn't make that designation ahead of the siege on the US Capitol this week by a pro-Trump mob disputing the official congressional ceremony for certifying President-elect Joe Biden's 2020 victory.

That was a massive failure, according to law enforcement experts who said better coordination at the top could have prevented the violent invasion of the Capitol that led to five deaths and shook Americans' faith in the national security apparatus and in democratic institutions.

The breakdown that led to the siege involved "a failure to anticipate, coordinate, and then plan," said Charles Marino, a former supervisory special agent in the US Secret Service. That's exactly what NSSEs can help accomplish, he said.

A former senior official at the DHS told @Politicsinsider it was "baffling" that an NSSE wasn't designated in advance of the mob's invasion on Wednesday, given how publicly Trump's supporters were about telegraphing their plans & calling for an armed revolution on social media.

The absence of that designation "gave us what I think we saw" on Wednesday, the former DHS official said, "which was an underestimation by the leadership of the Capitol Police as to what was coming, even though the signals were there that this had the potential to go south."

IMPORTANT accountability journalism here from @rbravender - Worth a @businessinsider subscription if you don't have one yet. Here's how to sign up: businessinsider.com/subscription