State authorities have beefed up security this weekend ahead of Democrat Joe Biden's swearing-in ceremony on January 20 and out of concern over potential armed protests on Sunday.

Authorities are hoping to avoid a repeat of the deadly Capitol Hill violence by President Donald Trump's supporters on January 6.

With the Federal Bureau of Investigation's (FBI) warning of potential violence at all state capitols, governors across the country have declared a state of emergency and closed capitols to the public.

Far-right online forums have called for "an armed march on all state capitols" on Sunday, US media reported.

President Trump continues to level unfounded allegations of election fraud and said he would not participate in Biden's inauguration. On Wednesday, the House of Representatives impeached the outgoing president  for the Capitol Hill "insurrection" that killed five people, including a police officer.

Where are the protests expected to take place?

The pro-Trump demonstrations could take place at all state capitols starting on Sunday. Ramped up security arrangements could be seen from Atlanta, Georgia to Sacramento, California throughout the week.

The main target of protests could be the country's capital, where Biden will be inaugurated as the 46th president of the United States on Wednesday.

Thousands of National Guard troops have been deployed in Washington, with security forces blocking off streets downtown with concrete barriers.

Intelligence reports say that armed insurgents could possibly try to plant explosive devices at so-called "soft targets." Authorities have also warned that armed pro-Trump extremists, possibly carrying explosives, pose a threat to Washington as well as state capitals over the coming week.

On Saturday, security officials arrested a heavily armed man in Washington at a checkpoint near the US Capitol. The man, a Virginia resident, was taken into custody after police found him with a handgun and more than 500 rounds of ammunition, shotgun shells and a magazine for the gun, according to AFP news agency.

State authorities are also concerned about the possibility of anti-Trump counter protests and violent clashes.

On Friday, the FBI in Tallahassee arrested Daniel Alan Baker, a former US Army soldier, who posted a short video on YouTube, urging people to counter pro-Trump protesters in Florida.

"Baker issued a call to arms for like-minded individuals to violently confront protesters gathered at the Florida Capitol this Sunday," federal prosecutors said. "He specifically called for others to join him in encircling any protesters and confining them at the Capitol complex using firearms."

What measures have authorities taken?

Washington DC is under a state of high alert ahead of Biden's inauguration. The National Mall, which is normally a crowded place around presidential inaugurations, has been declared off-limits at the request of the Secret Service, which ensures the security of the president.

Troops started pouring into Washington on Saturday after state governors approved sending National Guard to safeguard the capital. More than 25,000 Guard are due in the city by early next week.

In Arizona, authorities have placed a double row of chain-link fencing around the state capitol. Security around the statehouses in Illinois, Ohio, Michigan and other states have also been increased.

National Guard troops and heavily armed state troops have been stationed at state capitals across the US.

Suzanne Spaulding, a former undersecretary for the Department of Homeland Security, said authorities disclosing enhanced security measures can be an effective deterrent.

"One of the ways you can potentially de-escalate a problem is with a strong security posture," said Spaulding. "You try to deter people from trying anything."

What to expect on Inauguration Day

Joe Biden will be sworn in as president and Kamala Harris as vice president at an inauguration ceremony on the West Front of the US Capitol on Wednesday. Authorities have decided to curtail the attendance due to the coronavirus pandemic and security concerns.

Following the swearing-in ceremony, Biden will participate in a socially distanced Pass in Review with members of the military on the Capitol's East Front.

According to US media reports, Biden, Harris and their spouses, along with former presidents Barack Obama, George W. Bush, Bill Clinton and their wives will lay a wreath at the Tomb of the Unknown Soldier in Arlington National Cemetery.

Biden will then receive a traditional presidential escort from 15th Street in Washington to the White House.

Instead of the inaugural parade, organizers plan to hold a televised "virtual parade across America."

shs/rs (AP, Reuters, AFP)