The chief of the general staff of the Russian military, Gen. Valery Gerasimov, the country’s highest ranking uniformed officer, made a visit to dangerous front-line positions in eastern Ukraine late last week in an effort to “change the course” of Russia’s flagging offensive there, according to a senior Ukrainian official. Two U.S. officials with knowledge of the visit also backed that assessment.

Ukrainian officials learned of the visit, the Ukrainian official said, but not in time to catch General Gerasimov. When Ukrainian forces launched an attack on one position visited by General Gerasimov, at School No. 12 in the Russian-controlled city of Izium on Saturday evening, he had already departed for Russia. Still, some 200 soldiers, including at least one general, were killed, the Ukrainian official said, speaking on condition of anonymity to discuss a sensitive military operation.

Two U.S. officials, who spoke on condition of anonymity to discuss confidential intelligence assessments, confirmed that General Gerasimov had been in eastern Ukraine for the past couple days, but had no information about the attack on the Russian base.