A cross-border incursion into the Russian region of Belgorod on Monday put the Free Russia Legion under the spotlight, prompting questions about this mysterious paramilitary unit of anti-Putin Russians.

Russians fighting for Ukraine crossed the border north of Kharkiv into Russia’s Belgorod region on Monday night, prompting accusations from Moscow and denials from Kyiv. A paramilitary group called the Free Russia Legion (and another known as the Russian Volunteer Corps) later claimed responsibility for the incursion, prompting a new round of questions about the group: Who are they and what kind of weaponry do they have?

>> Read more: Pro-Kyiv Russian group says it 'didn't lose a single soldier' in cross-border raids on Belgorod

Founded with just 100 fighters, it is difficult to know how large the Free Russia Legion is today or where it has been active. But some analysts believe it has grown significantly since its inception.

Read more on FRANCE 24 English

Read also:
Ukraine unveils plan for recaptured Crimea – but West ‘reluctant’ to help
St Petersburg café killing exposes Russia’s security woes
A small step across the Dnipro River, a giant leap for Ukraine’s counteroffensive?