Once sidelined as a threat to the Kremlin, Russia's nationalists are emerging as a driving force behind what President Vladimir Putin has dubbed Moscow's "special military operation" in Ukraine.

Moscow's military intervention in Ukraine has done wonders for the career of nationalist blogger Roman Antonovsky, whose air time has spiked since fierce fighting broke out in February.

"Patriotism is the newest fad in Russia," the 42-year-old marketing specialist with glistening eyes and a handlebar mustache reminiscent of Russia's imperial era said before taking to the stage at a patriotic concert in Moscow.

"I like your faces. They haven't been disfigured by liberalism!" he told the like-minded crowd, before reading out nationalist poems.

The nationalists' hardline support for the campaign has even emboldened them to unleash rare criticism of officials they deem responsible for mistakes on the battlefield.

After setbacks like in Ukraine's northeast Kharkiv region and the southern city of Kherson, nationalists have lashed out at generals, demanded a general mobilization and even for the use of nuclear weapons.

'Russophobia has united us'

Their growing clout was on display in August at the funeral of Daria Dugina – the daughter of far-right political figure Alexander Dugin –after her death in a car bomb blamed on Ukraine.

Hundreds gathered for the memorial service in Moscow and condolences poured in, including from Putin.

Bloggers, journalists and intellectuals with nationalist views once confined to social media now get frequent air time on Russian state TV.

"The Kremlin needs the nationalists to support the special military operation," sociologist Lev Gudkov, head of independent pollster Levada Centre, told Agence France-Presse (AFP).

Research carried out by the Levada Centre shows that 78% of Russians believe Russia is a "great country surrounded by enemies," Gudkov said.

And a growing sense of Russia's isolation is a popular message for Russia's new patriots to espouse.

In blog posts and on radio, Antonovsky speaks up for "the great Russian Empire" as "the last bastion of traditional values".

He blasts what he describes as the liberal West and calls for a purge in Russia of "Russophobes" and to nationalize the media.

"Western Russophobia," he says, "has united us."

'Marriage of convenience'

Valery Romanov, a student, says some young people are drawn to Russian history and nationalist voices partly to better understand "what is happening now."

"Nationalism is not necessarily extremism," the 19-year-old said. "It's the highest form of patriotism."

He also manages logistics at the Black Hundred publishing house named after a monarchist and ultra-nationalist movement in Russia in the early 20th century.

Two of his friends, he told AFP, took a year off from studying to fight in Ukraine.

Romanov, however, is contributing by collecting donations of medicine, food and clothes to send to the front.

Twenty-seven-year-old researcher Daniil Makhnitsky, who considers himself a "national-democrat" is the founder of a small political group called "Society.Future," which is also collecting donations for Russian troops.

Their next truck will leave with 2,300 first-aid kits, he said.

"Europe thought sanctions would push us to overthrow Putin. But they had the opposite affect: Russian patriotism is booming," he said.

Gudkov, the sociologist, says the rising nationalist tide that currently serves the Kremlin has potential drawbacks.

"This imperial chauvinism could be very dangerous. It could become a dominant political force in the country due to the weakness of civil society," he says.

Makhnitsky has "no illusions" about the Kremlin's tolerance for the movement.

"It's a marriage of convenience," he said. "Once a peace deal is signed, it will be over."