Three armed groups, the Freedom of Russia legion, Russian Volunteer Corps and Siberian Battalion, launched a cross-border assault from Ukraine into Russia this week. Kyiv denies any role and says the attackers are Russian, but Moscow calls them Ukrainian "terrorist formations". It is unclear how the Ukraine-based groups got hold of advanced weaponry, tanks and armoured vehicles to raid at least two Russian regions. Here is what we know about the groups. FREEDOM OF RUSSIA LEGION The Freedom of Russia Legion says it was formed in spring 2022 "out of the wish of Russians to fight together with the Ukrainian...