Metal fences, concrete barriers and security checkpoints still line many the walkways and cross streets of the National Mall – extending from the U.S. Capitol down past some of Washington’s most noted landmarks – as the nation prepares to swear in its 47^th president.

But while the 0.6-square-kilometer (146-acre) swath of land is often the highlight of many a tourist visit, it is no longer the focus of security efforts for when President-elect Donald Trump takes the oath of office for a second time.

Frigid temperatures forecast for much of Monday led Trump to move the festivities inside – the inauguration to the U.S. Capitol Rotunda and the traditional inaugural parade to the nearby Capital One Arena.

The changes, first announced Friday, presented a last-minute hitch for security and law enforcement officials, who had been planning for the inauguration for the past year.

And it has left them, and the approximately 25,000 law enforcement and military personnel charged with security, with multiple challenges.

“We will shift those assets,” said the U.S. Secret Service’s Matt McCool, briefing reporters Sunday.

“We have not cut anything from what our original plan was,” he said. “I’m very confident, with our partners here, we will be ready.”

The numbers could make the situation especially trying.

Organizers had expected about 250,000 ticketed guests to descend on the U.S. Capitol and the National Mall to watch the inauguration.

Only a select few will be allowed into the Capitol Rotunda, which accommodates just 600 people. And the Capital One Area seats just 20,000.

If even just a fraction of the 250,000 people who had planned on attending the inauguration try to get to the arena, there could be a crunch.

Washington Metropolitan Police Chief Pamela Smith said Sunday her force, bolstered by and about 4,000 police officers from across the U.S., will be ready.

“Nothing has really changed,” Smith told reporters. “The police officers that were committed and dedicated to coming here, we’ll be flexible in how we’ll adjust [their] movement. … So, we will still have police officers in places and spaces around our city as we initially planned.”

Some of those officers, Smith said, will still be assigned to the original parade route in anticipation that some people will try to get a glimpse of the presidential motorcade as it goes by.

U.S. Capitol Police said they also anticipate having officers on the periphery of the West Front of the Capitol – now closed off with the inauguration moved indoors – ready to direct ticketed guests who will no longer be able to attend.

In addition, the inaugural security contingent, which includes the U.S. Secret Service, the FBI, U.S. Capitol Police, Washington Metropolitan Police, and some 7,800 members of the U.S. Army and Air National Guard, will all be coordinated from a command center linked into an expanded network of cameras keeping watch on the city.

And though security measures in some areas, including along parts of the National Mall, have been relaxed, officials said there will be plenty of reminders for anyone coming to Washington that this is no ordinary time.

“They will see tactical teams,” McCool said, during an earlier briefing with reporters last week. “They’ll see, officers and agents on rooftops, they’ll see checkpoints. They’ll see road closures and barriers in concrete.”

Even before the inauguration was moved inside, officials had been preparing for what they described as “a higher threat environment,” cautioning the security plans for this inauguration were already more robust than in the past.

“The biggest threat, I think, for all of us remains the lone actor,” said Capitol Police Chief Tom Manger. “That threat … remains the biggest justification for us being on this heightened stage state of alert.”

Those concerns were heightened following the New Year’s Day terror attack and truck ramming in New Orleans and the Las Vegas Cybertruck explosion outside the Trump International Hotel in Las Vegas, Nevada.

Earlier this month Capitol Police arrested two men suspected of trying to disrupt the state funeral for former U.S. President Jimmy Carter, one who tried to bring knives and a machete into the Capitol and another who set their car on fire.

Research, including a recent survey by the University of Chicago Project on Security and Threats, adds to the concerns.

“Over 5% of the American public supports the use of force to prevent Donald Trump from becoming president,” Robert Pape, the project’s director, told VOA.

“That equates to 14,000,000 American adults,” he said. “That’s an unfortunately disturbing number.”

Already, Trump was also the target of two attempted assassinations.

There is also an ongoing threat from Iran. Despite repeated Iranian denials, U.S. security and law enforcement officials have accused Tehran of trying to kill Trump, unveiling one plot set to be carried out last year, in the days after the U.S. presidential election.

For now, though, U.S. officials see no signs of impending trouble.

“The FBI is not currently tracking any credible or specific threats to the inaugural ceremony or the Capitol complex,” the bureau’s Washington Field Office told VOA. “We will continue to work closely with our partners to share information and identify and disrupt any threats that may emerge.”

Another source for concern is the tens of thousands of protesters, though so far, there have been no major incidents.

Saturday’s People’s March, which was permitted to have as many as 50,000 protesters, sparked only brief tensions with Trump supporters.

Another group, called We Fight Back, has permits for protests involving about 10,000 people in across several locations on Monday.

“Please note that [we] will ensure your right to peacefully protest and assemble,” said the Metropolitan Police Department’s Smith.

“However, I want to reiterate, as I always have, that violence, destruction and unlawful behavior will not be tolerated,” she said. “Offenders will face swift and decisive consequences … anyone who thinks that they can come into this city to destroy property, we will be prepared to deal with them.”

Kim Lewis contributed to this report.