As President Obama’s ceremonial swearing-in began at the Capitol on Monday, antiwar protesters forced a rolling roadblock for nearly a mile along 16th Street, north of the White House.

With banners, bullhorns and a fleet of faux steel-gray drones, more than 150 protesters chanted: “Stop the war. That is what we’re marching for.”

“I wanted the out-of-towners to recognize that there are some of us who believe he has not lived up to his potential,” Jim Schulman of CodePinkDC said of Obama.

The antiwar march represented the largest group of demonstrators decrying Obama administration policies. Most protests were small and scattered, coming from the left and the right of the political spectrum. It was a stark contrast from four years ago, when public expressions of discontent during the inauguration were primarily aimed at the man who had just left office, former president George W. Bush.

Among those marching on Monday were supporters of more than half a dozen groups, including and the Bradley Manning Network that backs the former intelligence analyst charged with leaking sensitive government documents to WikiLeaks, the anti-
secrecy group. They united under the banner of an antiwar group, the Arc of Justice, starting with a rally at Meridian Hill Park.

“We are here to mark the profound contradiction,” said Mauri Saalakhan of the Peace Thru Justice Foundation. “Our first African American president is presiding over a great expansion of war and killing. And we celebrate his inauguration on the day we remember a revolutionary.”

“The irony, I believe, is that if Dr. Martin Luther King was still alive, he would be here, with us, sharing our message,” he said.

Near the Washington Monument, a group called Occupy Monsanto started an impromptu dance party to remind Obama about his pledge to label genetically modified foods.

“We helped Obama get elected,” said organizer Adam Eidinger, who was joined by about a dozen others. “We brought carrots today, but we’re bringing sticks next time.”

Eidinger was referring to the 50 pounds of organic carrots the group handed out. With a portable sound system blaring dance music, activists danced and distributed fliers beneath a sign featuring an ear of corn with a fish tail.

Some inauguration attendees stopped and started dancing, too. But the party was short-lived.

A police officer told the group, which did not have a permit, to turn off the music.

At the D.C. government’s John A. Wilson Building, city officials held their own silent protest. On Mayor Vincent C. Gray’s parade reviewing stand, city leaders displayed a banner that read: “A more perfect union must include a free DC,” a message in support of statehood and voting rights for the District.

On Pennsylvania Avenue, about eight people from the Westboro Baptist Church, the small fundamentalist Christian church based in Topeka, Kan., held signs protesting abortion and gay rights.

Katherine Hochenbarger of Topeka held an anti-gay-marriage sign with a blood-drenched wedding cake topped by two figures meant to portray gay men. She said she was standing on an American flag “because it stands for a nation that hates God.”

There was some high-wire drama early in the day when a lone antiabortion protester climbed about 40 feet up a tree near the Capitol Reflecting Pool and for several hours refused to come down. Firefighters were unable to maneuver a ladder truck close to the tree because of security barriers. Initial efforts to talk him down were unsuccessful, according to Lon Walls, communications director for the D.C. Fire and Emergency Medical Services Department.

U.S. Capitol Police Chief Kim Dine said the protester was arrested, but the charges were unclear. Dine did not have immediate details of how the man was eventually removed or whether he came down on his own some five hours later.

In general, D.C. Police Chief Cathy L. Lanier told reporters that this year’s operations had gone more smoothly than for Obama’s first inauguration. D.C. police had arrested no protesters as of late afternoon and reported few major problems.

One exception occurred in the early morning hours Monday. Up to 60 anti-government activists, some wearing masks and carrying signs, damaged automated teller machines and a restaurant in the Mount Vernon Square area of downtown, according to police.

In one case, police said the vandals left anti-government literature behind.

“We’re looking at all avenues affiliated with anarchist groups,” said Officer Araz Alali, a D.C. police spokesman. “We’re taking this very seriously.”

About 40 self-described anarchists, many wearing bandannas on their faces, led police on their own three-hour parade, twisting and turning from McPherson Square to Pennsylvania Avenue and the edge of the security perimeter around the official parade route. They shouted at Obama supporters, calling the president a war criminal and a proxy for Wall Street bankers. More than once, inauguration-goers responded in kind, shouting down the group with chants of “O-bam-a.”

At times near Verizon Center, tensions rose as the group repeatedly deviated from a path police had cleared to keep them heading away from the parade route.

After reaching the dead end near Pennsylvania Avenue, protesters retraced their route with a block of police cars and motorcycles in tow. The group dissipated after reaching Dupont Circle, where they were drowned out by a drum circle of demonstrators seeking to draw attention to the complexities of Native American treaty obligations.