A Russian tank unit deliberately attacked another Russian position in Ukraine, report says, illustrating vicious rivalries within Putin's armyA Russian tank unit attacked another Russian position in Ukraine following an argument, the NYT said.The incident, part of a sweeping investigation by The New York Times, is one of the clearest examples of the vicious in-fighting that has plagued President Vladimir Putin's military throughout the war.A Russian drone operator who said he witnessed the episode told the paper that a Russian tank commander drove his T-90 tank toward a group of Russian national guard troops, fired at their checkpoint and blew it up.Other power centers include the mercenary Wagner group, led by Putin ally Yevgeny Prigozhin, and the forces led by Ramzan Kadyrov, the warlord who leads Russia's semi-autonomous region of Chechnya.The friction between these factions has spilled out into the open at times, including when Kadyrov and other Putin allies criticized the Russian military's retreat from a city in Ukraine in October."