Russia’s highest-ranking uniformed officer made a secret trip to the front lines in eastern Ukraine last week and narrowly escaped a Ukrainian attack, according to a report on Sunday.

Gen. Valery Gerasimov, the chief of the general staff of the Russian military, traveled to the Russian-controlled city of Izyum and made a stop at a school housing Russian troops, according to the report. Ukrainian officials learned of the visit and launched an attack on Saturday that killed some 200 Russian troops and a general, but not Gerasimov, who had already left for Russia, according to the New York Times report, which cited unnamed Ukrainian and U.S. officials.