They’ve been eager to fight ethnic Russians in the east of Ukraine from the very start, but the Ukrainian government has had a love-hate relationship with the Right Sector factions, a group of militias that embrace overtly fascist rhetoric and see crushing the rebels as just the first step.
“Officially, we are not here,” one such militia fighter was quoted as telling the Washington Post, as he and his forces, deployed along the frontlines, pass easily through military checkpoints. Unofficially, they are still part of the battle, and working closely with the military.
Their hostility to peace deals and comfort with neo-Nazi trappings make them a potential PR nightmare for Kiev, though in practice the promises to rein them in seem to have been sufficient distance for the government, and the fact that this reining in never involved doing anything was very much beside the point.
In the near-term, these ultranationalists will content themselves will attacks in the east, but the real danger for Kiev is what comes after the war. These groups were a key part of the regime change that put the current pro-West government in power, but many are very public in their view that they need another violent revolution to install an even more nationalist government.