Amid the tightest security this city has seen since the Civil War, law enforcement officials are contending not only with the potential for outside threats, but also with rising concerns about an insider attack by troops with a duty to protect the incoming president.
There have been no specific threats made against Mr Biden, but little is being left to chance.
The nation’s capital is essentially on lockdown.
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Riot fencing and razor wire reinforce the security zone on Capitol Hill; tanks and concrete barriers block the streets and the National Mall is closed. Fencing lines the perimeter of the US Capitol complex. There are checkpoints at major junctions.
Here’s what the nation’s capital looks like on this historic day.
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