The war in Ukraine looks to have created deep and lasting tensions between Russia's leadership in Moscow and its mercenary fighters on the ground, with acrimony between the two descending into openly hostile criticism and accusations of treachery this week. Yevgeny Prigozhin, the head of Russia's Wagner Group, a private military company whose fighters have been engaged in intense battles in Bakhmut in eastern Ukraine for months, could barely contain his rage on Tuesday when he lambasted Russia's military and political leadership, saying that promised supplies of ammunition for his mercenary fighters had still not been delivered. The latest rant...