Nearly 15 months since President Vladimir Putin sent troops into Ukraine in what he called "a special military operation", Moscow says it has still not achieved all of its aims as its forces brace for a Ukrainian counteroffensive which is backed by the United States and the NATO military alliance.

The Russian nationalist group, known as the "Club of Angry Patriots", said it was entering politics as an opposition party without any formal or informal instruction from the Kremlin but said it saw Putin as the only true guarantor of stability in modern Russia. The club was founded on March 17.

Girkin, a former Federal Security Service (FSB) officer who helped Russia annex Crimea in 2014 and then organise pro-Russian militias in eastern Ukraine, said the group hoped to prevent the collapse of Russia.

"A systemic crisis is brewing in Russia - or it is already in the grip of crisis - while the temperature of society is rising," Girkin told Reuters. "We are on the cusp of very grave internal political changes of a catastrophic character."

"All healthy forces need to create organisations which will take part in the political battle which is inevitable - and which has already started," he said.

In Putin's Russia, fiercely nationalist politicians and bloggers have since the war began increasingly taken on the role of critics of the military top brass who they say is failing due to incompetence, corruption and even treachery.

The Kremlin did not comment on Girkin's move. Putin, who is widely expected to run in the 2024 presidential election, says the special military operation will achieve all of its aims.

When asked by Reuters if he was naive to think he could announce such a political movement in Putin's Russia without the assent of the Kremlin, Girkin, 52, said: "I do hope you would not call me a naive person."

Girkin told reporters that it was clear that the battle for the "post-Putin" era had already begun inside the Russian elite.

"No matter how critical I am of Putin - Putin is currently the only legitimate figure in the Russian Federation," he said. If Putin was dislodged from power "it would mean the collapse of Russia," he said.

TURMOIL?

Girkin, who does not recognise Ukraine as a sovereign state and says much of it is part of Russia, said Russia would face defeat in the war unless it sacked top commanders, thieves and incompetents and began to fight in a much more serious way.

"If the current situation continues, then we will be defeated in this war," Girkin said, adding that victory for Russia would only be achieved if Ukrainian statehood was liquidated and cities including Kyiv controlled by Russia.

Echoing Putin's own framing of the war, Girkin said the West wanted to destroy Russia and trigger a coup to bring to power Western-backed politicians who would pillage Russia's natural resources and destroy Russian Slav culture.

"There will be no compromise: war will end with the Russian flag over Kyiv or the defeat of Russia with the aim of its partial occupation, its disarming and its desovereignisation."

He said the group had little money and no major financial sponsors and had been forced to scrabble together enough money for the announcement, which was made under tight security in a Soviet-era Moscow hotel built for the 1980 Olympics.

The group's other leaders include Chairman Pavel Gubarev, a pro-Russian fighter from eastern Ukraine, and Yuri Yevich, a military doctor, and Mikhail Aksel, a former member of the late Eduard Limonov's Other Russia movement.

"Our task is either to help our country avoid the turmoil that is approaching or to create those positions on which we will act in that turmoil to prevent the destruction of Russia as a state and as unique civilisation," Girkin said.

Girkin, who is also known as Igor Strelkov, was convicted last year in absentia by a Dutch court of murder for his role in the shooting down of Flight MH17 over Ukraine in 2014 with the loss of 298 passengers and crew. He has denied he was involved.