What is the Wagner Group, the Russian mercenary outfit in Ukraine?

A mural depicting Wagner Group mercenaries is seen vandalized with paint on a wall in Belgrade, Serbia, on Jan. 13. (Darko Vojinovic/AP)

Yevgeniy Prigozhin, head of the Kremlin-linked Wagner Group, a network of private security contractors that have taken up arms in Ukraine, put out a video Friday threatening to withdraw from the protracted, bloody battle over the Ukrainian city of Bakhmut and railing against Russian military leadership for failing to supply his forces with sufficient ammunition.

It remains to be seen if he will indeed withdraw — a move that would be catastrophic for Russia’s campaign to take the city and would probably carry political consequences.

The United States has designated the mercenary outfit a “significant transnational criminal organization.” The group has been accused of “mass executions, rape, child abductions, and physical abuse in the Central African Republic (CAR) and Mali,” Treasury Secretary Janet L. Yellen said in a statement this year.

Wagner boss threatens to pull out of Bakhmut, slams Russian military

The United States estimated earlier this year that about 50,000 Wagner fighters have deployed to Ukraine, the majority of whom were recruited from inside Russian prisons. Prigozhin, a close ally of Russian President Vladimir Putin, has joined his men on the front lines in Ukraine’s east.

The group’s presence on the battlefield has irked Russian military leaders, who have either ignored or dismissed Prigozhin’s criticism of military leadership.

Here are some facts about the Wagner Group and what it’s doing in Ukraine.

In Ukraine, a Russian mercenary group steps out of the shadows