The three gave themselves up after an hour, following negotiations with police. The head of the security police announced on Nov. 20 that the grenade was home-made. Whether it contained explosive material has yet to be established.
A prominent human rights campaigner praised the restraint shown by police in dealing with the group's Latvian wing, whom he described as "post-modern punks," but criticized encouragement of the National Bolsheviks by an ethnic-Russian MP and by Latvia's Russian-language press.
Latvian President Vaira Vike-Freiberga called on the authorities to take harsh action against the Russian National Bolsheviks and manifestations of extremism in Latvia.
Having unfurled red flags bearing hammer-and-sickle motifs, the three National Bolsheviks yelled demands through the mist surrounding the tower. These included the release from prison of four of their compatriots arrested in Daugavpils after jumping from a train passing through Latvia enroute from St. Petersburg to Kaliningrad on the night of Nov. 14, and the release of four members of the organization's Latvia wing who were arrested on Nov. 16 amidst fears of disruption to the Nov. 18 celebrations.
They also shouted opposition to plans for Latvia to join NATO, and their support for Vasilijs Kononovs, convicted this year of committing atrocities as a Soviet partisan during World War II.
The Russian Embassy also closed after it received warnings that it might be targeted by National Bolsheviks. Their actions were condemned by the Russian Federation's Ambassador to Latvia Alexander Udaltsov, in a statement to the Russian-language newspaper Chas.
"Extremist action threatening people's security cannot be justified," read the statement. "We have expressed our readiness to cooperate with the authorities."
A Riga city district court ordered that the three should be detained for 10 days while a case is prepared against them for hooliganism and illegally entering Latvia.
Judging from the National Bolsheviks' previous activities, the hand-grenade was probably not real, said Nils Muiznieks, director of the Center for Human Rights and Ethnic Studies in Riga.
"I would be surprised if it were real," he said. "If it is real then this is a negative new development."
The involvement of Russian citizens in National Bolshevik activities in Latvia is worrying, he added, because members of the organization in Russia are more inclined to use violence.
Muiznieks described the authorities' response to the occupation as "remarkably restrained," given the level of public pressure to imprison Latvia's National Bolsheviks.
"If they openly appeal for violence and discrimination then they are breaking the law," he said. "But you can't lock people up otherwise."
Latvian President Vaira Vike-Freiberga appeared to contribute to the pressure on the security services in her weekly interview on Latvia Radio.
"Extremism poses a threat to the state's existence, and national security, and should be fought absolutely," she said.
Muiznieks criticized Miroslav Mitrofanov, MP in the For Human Rights in a United Latvia coalition for expressing sympathy for the National Bolsheviks at a press conference in parliament.
"What mainstream politicians do in these situations is very important," said Muiznieks.
"Every society has fringe loonies, but sympathetic noises like this magnify the seriousness of the problem ten-fold."
Mitrofanov described the occupation as "courageous" and "deserving of respect," reported the Baltic News Service.
Latvia's National Bolsheviks are less of a security threat than the extra-parliamentary forces which operated in the early 1990s, said Muiznieks, and should not be confused with more typical brands of racist Russian nationalism.
"These people are virulently anti capitalist, anti-NATO and anti-globalist," he said.
"They glorify butcherous Soviet heroes like Beria for shock effect. But they are not like the Jew-hating nationalists in Russia.
The head of their Rezekne branch is black, the head of the Daugavpils branch is Roma and their chief ideologist is Jewish. I have no evidence to suggest that they are dangerous. They glorify violence but don't engage in it. If these grenades are real I will look at them as more serious than political theater."
But the attention paid to Latvia's small National Bolshevik movement by the Russian-language media is a problem, Muiznieks said.
Panorama Latvii kno-ws it can increase its circulation by giving an uncritical platform to these people who actually represent a social problem, as well as a law enforcement problem. The Russian-language media has made them icons. Most of the members are socially marginalized non-citizens who don't speak Latvian."
Fringe groups like the National Bolsheviks will become more visible in Latvia as the country opens up to the west and enters the European Union, says Muiznieks.
"Marginalization of youth needs to be addressed by building sports facilities and creating outreach programs," he said.
On Nov. 20, Latvian National Bolshevik Aio Beness told the newspaper Neatkariga Rita Avize that Latvian citizens in Russia would be held hostage until those who occupied St. Peter's are released.