The Russian Freedom Legion is the other group that claims to have been involved, also presenting themselves as Russians fighting for Ukraine and against Putin.

The legion says in its website which was formed last spring “out of the desire of the Russians themselves to fight against Putin’s armed gang in the ranks of the Armed Forces of Ukraine”.

The group calls on Russian soldiers and officers to join them in the fight for «Free Russia.»

It claims to be officially recognized by the Ukrainian army and to fight «under the leadership of the Ukrainian command.»

The group was banned as a terrorist organization by the Russian Supreme Court in March.

No particular names of Legion-affiliated leaders or people are shared on the group site. But a man nicknamed «César» has appeared in videos as his de facto spokesman.

“We are Russians, just like you,” he said in a video on the Monday before the raid, denouncing corruption and Putin’s crackdown on civil liberties. “We are coming home,” he said.

The Legion said in March that Russia launched a criminal case against «Caesar,» without identifying his real name.

The Legion also has a strong presence on Telegram, with more than a quarter of a million subscribers, calling themselves «free citizens of Russia.»

Earlier this month, RVC vowed to fight alongside the Legion «despite a different ideological basis.» It is not clear how many fighters are in each group.

“The Russian Volunteer Corps seems especially drawn to Russian nationalists and neo-Nazis, while the Legion seems to be less politically aligned,” Mark Galeotti, who runs Russia-focused consultancy Mayak Intelligence, told NBC News.

“They share the desire to see the Putin regime fall and believe that a victory for Ukraine is the best way to further this goal,” Galeotti said.

What is your motivation?

Kapustin, the RVC commander, told reporters near the Russian border on Wednesday that his group does not hide the right-wing views of some of its members, but does not believe that being called a neo-Nazi is an insult.

«You will never find me waving a swastika flag, you will never find me, I don’t know, raising my hand in a Hitler salute,» he said.

Sporting a goatee and an all-black military uniform, Kapustin touted the success of the Belgorod raid and said a broader operation it was being planned.

The group says it fully recognizes Ukraine’s territorial integrity and considers Putin’s war in Ukraine «criminal». It lists the “overthrow of the ruling regime in Russia” as one of its goals.

Meanwhile, Alexei Baranovsky, the spokesman for the Legion’s political wing, told Reuters the raid was «the first step in the main goal of overthrowing the Putin regime by armed force.»

In a post on the group’s Telegram channel on Wednesday, the Legion promised to return soon. “Belgorod, Bryansk, Kursk, Voronezh, Rostov, Moscow, wait for us,” the post read.

The group’s manifesto calls Putin’s regime «dictatorial» and says they are fighting against it and «for true freedom for all Russians.» It also calls on both ethnic Russians and minorities in the country to rise up against the Russian leader.

“It is clear that the Russian Freedom Legion and the Russian Volunteer Corps are predominantly Russian groups, self-proclaimed ‘partisans’ trying to overthrow Putin’s government, ranging from neo-Nazis soccer thugs to celebrity wannabes and even some semi-serious political reformers,” said Michael Clarke, visiting professor of war studies at King’s College London.

“They are not ‘liberals’, but rather hardline Russian nationalists, but not of the Putin variety,” Clarke added.

NBC News has reached out to both groups for comment, but they did not immediately respond.

What is your connection to Ukraine?

The Kremlin does not dispute that some of the fighters involved in this week’s raid could be ethnic Russians, but sees them as «Ukrainian militants coming from Ukraine,» according to spokesman Dmitry Peskov.

Ukraine has denied involvement in the actions of either group, calling them «Russian patriots» who decided to rise up against the Kremlin.

The groups’ extreme views and evidence that the fighters involved in this week’s raid appeared to be using US armored vehicles have raised questions for Washington, which has sought to ensure equipment sent to Kiev is not used in attacks on Russian soil. .

Andriy Yusov, a spokesman for Ukraine’s military intelligence directorate, told NBC News that the raid was carried out «exclusively by citizens of the Russian Federation» who had acted «completely autonomously» and that Ukraine did not coordinate with them.

The Legion’s Baranovsky said the unit was part of Ukraine’s international brigade, but denied the raid was coordinated with Ukrainian authorities.

But Kapustin, the RVC commander, said Ukraine «encouraged» the group’s actions in Belgorod, and that they «consult» their actions with the Ukrainian military, though he said anything they do outside the country’s borders «is ours.» own decision.»

Experts also questioned kyiv’s narrative that it was a purely Russian affair.

“There is really no question that the Russian volunteer units are armed and controlled by Ukraine,” Galeotti said.

«Although it is in Kiev’s interest to pretend that this was simply an undertaking by Russian patriots, it would only have been carried out on the orders of the GUR, or at least with its approval,» he added, referring to the intelligence branch of the Ukrainian Defense Ministry. .