CHICAGO — Police clashed with scores of protesters Sunday after more than 2,000 demonstrators marched peacefully to the edge of the NATO summit where President Obama was meeting with world leaders.

Protesters shouting "Shut down NATO" threw bottles at officers wearing riot helmets and wielding batons. About 30 minutes after a city permit for the march expired, police began forcibly dispersing the crowd by driving the demonstrators out of the streets near the McCormick Place convention center where the summit convened.

The march began several hours after activists hacked the city's website and prosecutors announced the filing of charges against two more men accused of planning to disrupt the NATO gathering with homemade bombs.

Charged Sunday were Sebastian Senakiewicz, 24, and Mark Neiweem, 28, both of Chicago, according to Cook County State's Attorney Anita Alvarez. She announced charges against three men from out of state Saturday.

"While the cases that were charged in court today arose from related investigations, the two defendants are not charged with any involvement in the terrorist case from yesterday, and today's cases are separate matters," Alvarez said in a statement.

The three out-of-state men charged Saturday were accused of making Molotov cocktails to hurl at the president's re-election campaign headquarters in Chicago, at Mayor Rahm Emanuel's home and at financial institutions and police stations, according to a statement issued by Alvarez and Chicago Police Superintendent Garry McCarthy.

Defendant Brian Church, 22, is from Fort Lauderdale, Fla., according to prosecutors and police. Jared Chase, 27, is originally from Keene, N.H., and Brent Betterly, 24, told police he is from Massachusetts.

"The investigation began in early May 2012, and revealed that the defendants are self-proclaimed anarchists and members of the 'Black Bloc' group, who traveled together from Florida to the Chicago area in preparation for committing terrorist acts of violence and destruction," according to Alvarez and McCarthy.

The "black bloc" tactic also surfaced last month in Seattle. Anarchists responsible for much of the violence during Seattle's May Day protests employed the tactic, disguising themselves and making it difficult for law enforcement to arrest specific individuals.

About 75 black-clad protesters used long poles, hammers and other objects to smash windows on vehicles and at some downtown Seattle businesses, including NikeTown, then shed the black clothes to merge back into the crowd of nonviolent protesters.

War, budget and more

In Chicago, demonstrators' grievances, expressed in chants and on signs, included condemnations of NATO forces in Afghanistan, Israel's treatment of Palestinians, Wall Street and domestic budget cuts to education.

More than two dozen military veterans appeared on a stage with the summit site as a backdrop to renounce the medals they had received for their service. Among the crowd were former members of the military who had taken part in the war in Afghanistan, the chief subject of the NATO meeting.

"The military handed out cheap tokens like this to soldiers and service members to fill the void where their conscience used to be," said Greg Miller, who identified himself as a U.S. Army veteran, as he tossed a Global War on Terrorism Medal and a National Defense Medal from the stage.

A block from where Miller spoke, the police crackdown began when about 20 police officers riding bicycles and wearing helmets, backed by scores of officers wearing body armor and carrying batons, blocked the north end of the procession.

Police Superintendent McCarthy said 45 people were arrested and four officers injured. One was stabbed in the leg.

Both of the men who were accused Sunday of planning to disrupt the gathering made their initial appearances in Cook County Criminal Court. Senakiewicz, a native of Poland, is accused of making a false terrorist threat, a felony, while Neiweem is charged with soliciting possession of explosives and incendiary devices.

The judge set bond for Senakiewicz at $750,000. Bond for Neiweem was set at $500,000. Outside the courtroom, lawyers for the men said they would enter not-guilty pleas.

In court, Assistant State's Attorney Patrick Morley said Senakiewicz "indicated he is an anarchist." Senakiewicz allegedly told associates he was hiding delayed-detonation explosives, capable of destroying a railroad bridge, in the center of hollowed-out Harry Potter books.

Police obtained a search warrant of Senakiewicz's home and found no explosive devices, Morley said.

Demonized group?

Senakiewicz's lawyer, Molly Armour, said he was a "political man who is being targeted because of his beliefs."

Neiweem was accused of handing an associate a list of parts he needed for building pipe bombs, including PVC pipes, caps and model rocketry engines, Morley said in court.

Both men were arrested Thursday and held for at least 66 hours before their initial court appearances, Sarah Gelsomino, an attorney with the National Lawyers Guild, said after Sunday's hearing.

"None of these individuals had any explosives," she said, asserting they'd been held solely because they were anarchists. "It's not illegal to hold a political belief, even anarchism."

The men charged Sunday and those who appeared in court Saturday had been arrested after contacts with two possible police informants, a woman known only as "Gloves" and a man known only as "Mo," said Gelsomino and attorney Steven Saltzman, who appeared in court with Neiweem.

Mo and Gloves began fraternizing with Occupy Chicago protesters during a May 1 rally in the city's federal plaza, Gelsomino said, adding that it's unclear what relationship they may have with the Police Department.

"These are very sensationalized charges," said Gelsomino, whose group is organizing a defense team for the men. She called the allegations "an attempt to demonize these people in the public eye."

G-8 summit

Organizers of Sunday's rally had initially predicted tens of thousands of protesters this weekend. But that was when the G-8 Summit of leading industrial nations was also scheduled to be in Chicago. Earlier this year, President Obama moved the Group of 8 economic meeting to Camp David, in rural Maryland.

Chicago kept the NATO summit, the first to be held in an American city other than Washington. It is not addressing the economy specifically. That left activists with the challenge of persuading groups as diverse as teachers, nurses and union laborers to show up for the Chicago protests even though the summit's main focus doesn't align with their most heartfelt issues.

For its part, the Police Department has been trying to avoid the sorts of violent confrontations that have marred the city's history, from the 1968 Democratic National Convention to mass arrests during an Iraq protest in 2003. The city recently paid $6.2 million to settle a lawsuit over police conduct during the 2003 protests.

Additional information from Chicago Tribune, The Associated Press, The Washington Post and The Seattle Times archives