Protesters are expected to descend on statehouses across the United States yesterday in support of baseless claims that electoral fraud robbed President Donald Trump of a second term, as law enforcement officials girded for possible violence.

More than a dozen states have activated National Guard troops to help secure their capitol buildings following an FBI warning of armed protests, with right-wing extremists emboldened by the deadly attack on the US Capitol in Washington on Jan. 6. At least 5 people were killed on that day.

There were scattered demonstrations on Saturday, but statehouses remained mostly quiet. Security officials have eyed yesterday as the first major flashpoint as that is when the anti-government "boogaloo" movement made plans weeks ago to hold rallies in all 50 states.

While many states have erected fences or other barriers to secure their capitols, Texas and Kentucky have taken the further step of closing their capitol grounds to the public.

It is just days until Wednesday's Inauguration Day, when Democrat Joe Biden will be sworn in amid extraordinary security efforts in Washington, D.C.

The downtown area of the capital was virtually empty on Saturday, with streets near the Capitol closed and battalions of camouflaged National Guard soldiers taking up positions across the city center.

Authorities in Washington said they arrested a man with a loaded handgun and more than 500 rounds of ammunition at a security checkpoint, underscoring the tension in the US capital which is resembling a war zone.

However, the man said it was "an honest mistake," and that he was a private security guard who got lost on his way to work near the Capitol.

Meanwhile, US Justice Department investigators on friday they have not found any evidence yet that the rioters who ransacked the US Capitol last week intended to capture and kill any lawmakers.

Yesterday, NBC news reported that the FBI have launched an investigation on whether foreign governments, organisations or individuals provided financial support to people who helped plan and execute the January 6 attack on the Capitol.

As part of the investigation, the FBI is examining payments of $500,000 in bitcoin, apparently by a French national, to key figures and groups in the far right before the riot, one current and one former FBI official told NBC News.

The Chainalysis blog post, first highlighted by Yahoo News, said far-right podcaster Nick Fuentes received the most money, 13.5 BTC – worth about $250,000.

Separately, a joint threat assessment issued last week by the FBI, the Department of Homeland Security, and various other federal and DC-area police agencies noted  that since the deadly January 6 riot, "Russian, Iranian, and Chinese influence actors have seized the opportunity to amplify narratives in furtherance of their policy interest amid the presidential transition."

It was not clear whether the ramped up security presence might lead some protesters to stay at home.