Russian President Vladimir Putin has appointed Gen. Valery Gerasimov as the new top commander of Russian forces in Ukraine. 

Gerasimov, who has served as the chief of general staff of Russia’s armed forces since 2012, is replacing Gen. Sergey Surovikin, who has overseen the invasion since October. Surovikin was accordingly demoted to a deputy serving under Gerasimov. 

Gerasimov’s appointment comes as Russia is trying to turn the tide of the war after months of struggling to make advances amid a strong Ukrainian counteroffensive that has liberated thousands of square kilometers of Ukraine from Russian control. 

Russia appears to be on the precipice of making its most significant gain on the battlefield since August, having almost taken control of a small mining town called Soledar. 

The Russian Defense Ministry said in a Telegram post announcing Gerasimov’s appointment that he was chosen to help organize closer interactions between the branches of Russia’s armed forces and to improve the “effectiveness” of leading Russian soldiers. 

The BBC reported in 2012 that Gerasimov joined the military of the Soviet Union in 1977, becoming a member of the Northern Group of Forces stationed in Poland. 

He then served in the Far Eastern and Baltic military districts before becoming chief of staff of the 58th Army in the Northern Caucasus Military District in 1999, according to BBC. 

The Second Chechen War began later that year when fighting broke out between separatists from the Russian province of Chechnya and Russian forces. 

BBC reported that Gerasimov was involved in arresting a Russian army colonel named Yury Budanov, who was convicted of murdering a Chechen girl during the war. Gerasimov was appointed commander of the 58th Army in 2001 as the conflict continued. 

Gerasimov served as the chief of staff of the Far Eastern Military District, where he was reprimanded for a large outbreak of illness among the soldiers, from 2003 to 2005. He also served as the commander of military districts for St. Petersburg and Moscow and the Central Military District, which makes up a large part of central Russia. 

The Financial Times reported in 2017 that Gerasimov is known to be taciturn and does not make many public appearances. 

He argued in 2013 in a Russian newspaper that the lines between war and peace in the 21st century have become “blurred,” as wars are no longer being officially declared. He said world actors are instead using “special-operations forces” and “internal opposition” to establish a “permanently operating front.” 

Throughout much of the war in Ukraine, Putin has refused to call the conflict a war, instead referring to it as a special military operation. He called it a war for the first time last month. 

Gerasimov is married and has a son, the Financial Times reported. He was born in 1955 to a working-class family in the Russian city of Kazan, about 800 kilometers east of Moscow.