In a letter made public on Monday, Russian mercenary chief Yevgeny Prigozhin informed Defense Minister Sergei Shoigu that the Ukrainian army was preparing an impending attack to cut off his Wagner forces from the main body of Russian troops in eastern Ukraine.

The “large-scale onslaught,” according to Prigozhin, was scheduled for the end of March or the beginning of April, according to a letter made public by his press staff.

I ask you to take all necessary steps to prevent the Wagner private military company from being cut off from the Russian army’s main forces, since this would have a severe impact on the “special military operation,” as Moscow refers to its conflict in Ukraine.

It was the first time Prigozhin has published such correspondence with the defense minister, whom he has frequently criticized over the conduct of the war.

The unusual move appeared to have two possible aims: to wrongfoot Ukraine commanders and to seek to pin blame on Shoigu, not Prigozhin, if the purported Ukrainian maneuver proved successful.

Prigozhin said he was providing details of the Ukrainian plan and of his own proposal to counter it in an attachment to the letter, which he did not make public. He did not say how he knew of Ukraine’s intentions.

He said Wagner forces currently controlled 70% of the Ukrainian city of Bakhmut, which they have been trying to capture since last summer in the longest and bloodiest battle of the war.

In separate comments published by a regional news channel on Telegram, Prigozhin said there was a “high probability” that the southern Russian city of Belgorod would be one of the targets of the coming Ukrainian offensive.

He gave no evidence to support his assertion that Ukraine might launch a full-scale attack on a Russian city.

Russia has frequently accused Ukraine of mounting isolated cross-border strikes by drones and other means. Ukraine has not claimed responsibility for such incidents but has described them as “karma” for Russia’s invasion.