Tension between Yevgeny Prigozhin, head of Russia¡¯s Wagner private militia group, and the nation¡¯s defense establishment exploded in dramatic fashion on Friday. The mercenary chief vowed to punish Russian military leaders, saying Defense Minister Sergei Shoigu had orchestrated a missile attack that killed ¡°huge¡± numbers of his fighters. The Kremlin responded swiftly, denying the attack and accusing Prigozhin of mutiny.

The internal conflict is the biggest test of President Vladimir Putin¡¯s authority since he sent troops into Ukraine 16 months ago. In a short televised address to the nation on Saturday, Putin denounced the rebellion by Wagner forces and its leader as ¡°treason¡± and promised harsh punishment.

Here¡¯s what you need to know about the Wagner Group, its role in Russia¡¯s invasion of Ukraine, and why its leader is accused of mutiny.