Police and anti-NATO activists say they are prepared to prevent violence at this week's NATO summit in France and Germany, but conflicts are already simmering between demonstrators and authorities.

These days, representatives from peace organizations and groups critical of the North Atlantic Treaty Organization are not amused. They said police and security authorities are violating basic democratic rights for the sake of securing the NATO summit this Friday and Saturday in Strasbourg, France, and Kehl and Baden-Baden, Germany. The anti-NATO activists' attempts to stage peaceful protests have been massively curtailed, they said.

Monty Schaedel, head of the German Peace Association, a far-left group that has organized several anti-NATO demonstrations to take place over the coming days, said that a regional police chief had threatened protesters verbally to create an atmosphere of fear.

"They are trying everything to bully us," he said last week in Berlin.

Rainer Braun, head of the German section of the International Association of Lawyers Against Nuclear Arms, a group that wants NATO to be abolished, said authorities acted "paranoid."

Security accompanying NATO's 60th anniversary summit is indeed massive: 25,000 police will be located in Strasbourg, Kehl and Baden-Baden when the leaders of 26 NATO member states meet there April 3-4.

The three cities will turn into fortresses, with schools closing, manholes being sealed and French and German fighter jets on standby. Security for the summit will cost $146 million, but officials said the massive measures are necessary to prevent protests from turning violent and to act swiftly in case of a terrorist attack.

Between 10,000 and 40,000 anti-NATO activists are expected to flock to the area, and authorities said an estimated 2,000 to 3,000 of them are ready to use violence.

Officials in France and Germany have repeatedly compared this meeting's protest potential with that of the Group of Eight summit in 2007 in Heiligendamm, Germany. At the time, a black-clad mob known as the Black Block wreaked havoc in the nearby city of Rostock, hurling stones at police and torching shops. The brutality of the Rostock protests overshadowed the peaceful demonstrations that accompanied the summit.

Braun said the activists had learned from Rostock and are doing "everything to de-escalate the demonstrations" by staging protest trainings, having bouncers on site who deal with violent protesters and coordinating the marches with police. Braun added that his group was making sure that stones aren't brought to demonstrations. In Rostock, the Black Block had brought shopping carts full of stones as armament.

Anti-NATO activists are not happy, however, with police restrictions placed on demonstrations.

The route of a protest march planned for Friday in Baden-Baden has been shortened because officials "have concrete indications that public security is threatened," a spokesman of the regional government in Karlsruhe told United Press International in a telephone interview Tuesday.

Schaedel is mulling over whether to appeal that decision, but there are more restrictions that have sparked his ire. He said a group of demonstrators wanted to dress up as clowns to lend some comic relief to the otherwise tense protests, but authorities have warned that they would be treated as "Gefaehrder," or dangerous individuals. Protesters are not allowed to run, jump or carry water pistols.

"While the police are installing snipers all over Baden-Baden, we can't even bring plastic water pistols," Schaedel said.

But authorities said the restrictions placed on protests are in full compliance with German law. They are aimed at "taking the momentum away from groups that could make such a demonstration turn violent," a police spokesman told UPI in a telephone interview Tuesday.

That doesn't mean authorities are all about restrictions. They have also compiled an anti-conflict team of 82 experts, some of them psychologists, who are trained to de-escalate demonstrations.

"These are officers in uniform that will make the police measures transparent by explaining them to demonstrators," the police spokesman said.

It remains to be seen whether these experts can soothe the NATO activists, many of whom are unhappy with the overall situation ahead of the summit.

Activists have to camp several miles outside Strasbourg's city center, and some of their demonstrations in France have been canceled. Protesters also fear that they might be rendered immobile once the summit starts.

Officials have set aside the Schengen Agreement, which eases border controls between some EU countries, for the duration of the summit, and Schaedel said he expects controls to mainly target -- and thus delay -- protesters trying to get from one summit venue to the other. Anna Luczak, a lawyer on a legal team assisting the anti-NATO groups on the ground, said she and her colleagues are "ready to help if people aren't allowed to pass the border."

This unhappy atmosphere of mutual mistrust has done little to soothe the local population in the region.

In the otherwise sleepy town of Kehl, shop owners are planning to barricade their storefronts with wooden planks out of fear that manic protesters, during a large demonstration planned there for Saturday, would do to this city of 34,000 what they did to Rostock.

Braun said the people of Kehl shouldn't be afraid.

"We are very optimistic that everything will be peaceful and positive," he said.