The United States authorities decided that protesters are forbidden to wear masks back in the middle of the 20th century. In the first place, this measure was designed to fight the Ku Klux Klan movement. Many recollected this measure in the early 2010s when the streets of many American cities were flooded with members of the Occupy movement.
According to local laws, wearing masks during street protests is banned in at least a half dozen states. The violation of the established order is punishable not only by a fine, but also by an imprisonment of up to three years.
Even more severe punishment threatens the residents of Canada. The jail term for the same violation here is up to 10 years.
Such a strict law in Canada was adopted back in 2013. The reason was the large-scale clashes of students with police.
The same laws are in force in Western Europe. For example, Germany banned helmets, masks, shields, hoods and all that can help a rally participant hide his or her identity. Such a law was passed in Germany in the late '80s. The violation leads to an imprisonment of up to one year.
In France, the rules of 'social dress code' are even more stringent.
In the Fifth Republic, you are simply not allowed to appear in public with a covered face.
That is, masks, helmets, balaclavas and many other accessories are to be left home. Otherwise you pay a fine. In that country, the relevant law was adopted in 2010.
In Spain the offenders are punished by a fine of up to 30,000 euros.
That is why the detentions of anarchists during the protests in Minsk on March 15 can be considered not only legitimate, but also generally accepted in most civilized countries. In addition, violation of the law on mass events in Belarus is punishable only by 15 days in jail or by a fine of up to 690 rubles (about $350).
It should be understood that flying a red and black flag in Belarus (as it was done during Ukraine's Euromaidan) is not only an expensive but also illegal idea. If anarchists want to destroy any state, any state has the right to defend itself. This is a practice accepted worldwide.