MOSCOW — Forcing a showdown with the government of President Vladimir Putin, leaders of the Russian political opposition took to the streets Saturday afternoon for an unsanctioned demonstration in a symbolic square in Moscow that is home to the headquarters of the federal security services as well as a monument to victims of Soviet political repression.
Bundled up against the cold and wind, with the temperature hovering at 5 degrees, about 2,000 demonstrators gathered in Lubyanka Square, not far from the Kremlin. They were met by a huge contingent of riot police, who quickly cordoned off the area and began making arrests.
The protest without a permit was a pointed act of defiance, particularly by the two most prominent opposition leaders: Alexei Navalny, an anti-corruption activist, and Sergei Udaltsov of the Left Front, a radical socialist group. Navalny and Udaltsov face a growing number of criminal charges and have lived for weeks with the prospect of imminent arrest.
Udaltsov was seized by the riot police moments after he arrived, at about 3 p.m., and hustled into a police van.
''I am not violating any laws,'' he shouted as he was taken away. ''Russia will be free.''
Navalny, by contrast, arrived surrounded by a large scrum of photographers and worked the crowd like a politician on a rope line, shaking hands with supporters. He seemed buoyant and carefree and said, ''OK, let's stand here awhile.'' The mob around him seemed to forestall his arrest, but not for long. He was detained about an hour after his arrival.
The crowd was a fraction of the size of previous rallies this year, suggesting that interest may be waning. The inability of the opposition leaders and the authorities to agree on the terms for a protest permit also suggested that each side's resolve might be hardening.
By attending the rally, demonstrators showed they were unbowed by a law signed by Putin in June that imposes steep fines — of more than $9,000 for participants and more than $18,000 for organizers — for taking part in unsanctioned protests.