Yevgeny Prigozhin, the leader of the Russian mercenary army the Wagner Group, reportedly confronted Russian President Vladimir Putin over the mismanagement of Russia’s combat operations in Ukraine. Prigozhin’s Wagner Group has been heavily involved in Russian combat efforts in Ukraine and some observers believe his influence in Russian politics is growing.

The Daily Express reported on Saturday, based on U.S. intelligence claims, that the Wagner Group’s leader raised issue with Russia’s handling of the war in Ukraine when he confronted Putin face-to-face. The Daily Express reported their meeting was “tense” and significant enough to warrant mention in one of President Joe Biden’s recent daily intelligence briefings.

In their meeting, Prigozhin reportedly criticized Russian Defense Minister Sergei Shoigu. Prigozhin has reportedly been calling for Putin to replace Shoigu and give his mercenary forces more funding in Ukraine.

While Prigozhin reportedly confronted Putin specifically about Shoigu’s handling of the war effort, some Russia observers believe the mercenary leader could be trying to usurp Putin’s own political power.