Capitol security has always been partly about appearances, something that became clear again during the Senate hearing Tuesday about the lessons learned from the Jan. 6 riot as Congress certified the 2020 presidential election results.

Even before all the details of that riot have come to light, a bipartisan group of lawmakers expressed alarm about the continued use of National Guard troops and barbed-wire fencing on the nearly 60-acre campus, warning against turning the nation’s most important symbol of democracy into a military encampment.

This push and pull — actual safety vs. the importance of symbolic freedom — came to a head at Tuesday’s hearing.

Testimony showed that in the days leading up to the attack, some officials wondered whether the threat was serious enough to warrant a stronger military presence on the intentionally open Capitol grounds. As the riot unfolded that afternoon, Pentagon officials expressed concern about the appearance of “boots on the ground.”

Then came the worst ransacking of the Capitol since British troops attacked the building in 1814. A Capitol police officer and four others died as a result of the violence.

Now, seven weeks later, many lawmakers are concerned about the optics of the ongoing military presence without a specific, clear threat of another attack.

“No one has any idea why we have the National Guard here,” Sen. Rick Scott (R-Fla.) said toward the end of Tuesday’s hearing.

Scott professed that he was “flabbergasted” that 5,000 Guard troops were still serving on a rotation protecting the Capitol.

Other senators warned that this beacon of the free world must remain open to the public. “How do we allow the American people to go in the Rotunda, to tour the Capitol, to picnic on the grounds, to play with their kids?” Sen. Angus King (I-Maine) asked the security experts. “It seems to me that going forward, that’s really one of the challenges. We want security, but we don’t — I would hate to see the U.S. Capitol turned into a fortress.”

It was left to Sen. Amy Klobuchar (D-Minn.), chairman of the Rules Committee, which co-hosted the hearing, to play the role of hardened realist, telling her colleagues that security measures had to change after Jan. 6 exposed so many weaknesses.

“No, it does not have to be barbed wire, and of course, this is a public building and you want the school groups and you want the veterans and we want people to be able to visit here. But that doesn’t mean that we don’t make some smart security changes,” she said.

The global coronavirus pandemic has temporarily resolved those issues, because the public has been barred from the Capitol since March, when it became impossible to allow the usual 10,000 to 30,000 visitors per day into the building.

But congressional officials have refused to speculate about what conditions must be met before the public will be allowed back to watch the House and Senate proceedings and to roam the office buildings to visit their members of Congress.

The last great reckoning with congressional security came after the 2001 terrorist attacks.

That prompted the push to turn the original proposals for the Capitol Visitors Center into a massive security facility. At more than 675,000 square feet, the three-level structure opened in 2008 and now houses the Capitol Police, two secure bunkers for intelligence briefings and other rooms that were designed to be evacuation sites for lawmakers in the event of an attack.

Proposals then to set up security fencing fell by the wayside and instead led to the placement of bollards, steel posts drilled deep into the ground. They stand guard around the congressional campus and federal buildings across Washington.

But Jan. 6 showed the limitations of fighting the most recent war. Those protective measures were designed to deal with more traditional forms of terrorism, such as preventing suicide car bombers from driving onto the grounds or into federal buildings.

And, as former Capitol Police chief Steven A. Sund testified Tuesday, the force has trained for attacks like the 2008 incident in Mumbai in which a group of 10 terrorists carried out shootings and bombings.

No one was prepared for how to handle an invading force of hundreds or thousands of Americans trying to break into the Capitol and attack lawmakers.

Even the supposedly mighty visitors center — with its open connection to the Capitol building through elevators and escalators — was breached on Jan. 6.

As this month’s impeachment trial, testimony showed that Senate Majority Leader Charles E. Schumer (D-N.Y.) and his security team first went into the visitors center, only to race away in another direction when they came within sight of rioters.

Now, experts such as Sund think the campus needs to buffer itself with secure windows and doors, and some form of fencing several blocks out.

“There are options for maintaining an open environment, an open-campus type of environment while putting some substantial physical security measures in place, both for the building, the skin of the building, as well as farther out,” Sund told senators Tuesday. “You know, time and distance is our best friend. And the most important thing is to provide some kind of protection farther out.”

The extent of those security measures eventually will run into a fight from local officials with the District government, who are already bristling at the militarized setup around the Capitol. Since Jan. 6, troops have closed down two major thoroughfares, Independence and Constitution avenues, for several blocks around the House and the Senate, the sort of move that would radically alter the city’s traffic grid if it becomes permanent.

“There needs to be a reimagining of the security posture there. Something certainly should be there, but I’m not exactly sure if the answer to that is razor wire and the deployment that we currently see,” D.C. Police Chief Robert J. Contee III testified Tuesday.

Maybe the barbed wire will come down soon, but for now the National Guard is slated to be on hand at least through mid-March, and, in her closing remarks, Klobuchar tried to brace her colleagues for a long period of tighter security.

“We know after 9/11, the National Guard held for quite a while,” she said.

But that left many senators worried about the optics, unable to answer what they thought was a straightforward question.

“How do we protect the Capitol from either an angry mob or probably more likely one or two or three malignant actors,” King asked, “without turning it into a fortress?”