What is the Wagner Group, Russia’s mercenary organisation?

RUSSIA MASSED around 190,000 troops on Ukraine’s border before it invaded. But there may be other, more shadowy Russian forces fighting there. According to a report in the Times on February 28th, more than 400 mercenaries belonging to Russia’s Wagner Group have been sent to Kyiv to assassinate Volodymyr Zelensky, Ukraine’s president. American officials say they have seen some indication of Wagner’s involvement in the war. Those reports have not been confirmed, but Wagner’s presence would not be a surprise. For years Ukraine has accused the private military organisation, which appears to have close ties to the Kremlin, of fighting in Luhansk and Donetsk, the disputed parts of eastern Ukraine. The mercenaries, who have also reportedly fought in both northern and sub-Saharan Africa, have been accused of torture, rape and extrajudicial killings. What is the Wagner Group, and how is it linked to the Russian state?