Russian Army Gen. Aleksandr Dvornikov, the man chosen to lead the next phase of Moscow’s war in Ukraine, wrote in a military newspaper in 2018 that in modern warfare, “the main task is not the physical destruction of the enemy, but the complete subordination of him to one’s will.”

An architect of Russia’s military intervention in Syria, where Russian airstrikes hit civilian targets including hospitals, Gen. Dvornikov has since the start of the invasion in February led the troops that have pushed northward from Crimea and captured a swath of territory in southern Ukraine.

He now will become the overall commander, according to Western officials, as Russia refocuses on the south and eastern Ukraine’s Donbas region after failing to capture Kyiv, the capital, and Kharkiv, the country’s second-largest city, in the north, in the face of fierce resistance that inflicted heavy casualties.

Military analysts blame the stalled Russian offensive in part on a divided command structure that led to poor coordination. Now Russia has shifted its forces to the east and unified them under Gen. Dvornikov’s command, focusing its goals on seizing territory in the Donbas area that it doesn’t yet control, according to Western officials.

Russian troops on the move in 2019 in Syria, where Army Gen. Aleksandr Dvornikov has deep experience.

Photo: Bekir Kasim/Anadolu Agency/Getty Images

Moscow hasn’t issued an official announcement about his role. Russia’s Defense Ministry didn’t respond to a request for comment.

Military analysts say Gen. Dvornikov, 60 years old, is a logical choice to lead the new phase of Russia’s campaign. In addition to being the most senior officer and tipped to eventually replace Chief of General Staff Valery Gerasimov, the military analysts said, he has, since 2016, led the Southern Military District, which is responsible for Russia’s operations in the Donbas. Moscow first fomented a rebellion there in 2014—a claim the Kremlin denies—and the conflict dragged on for eight years before Russia launched its full-scale invasion in February.

“Dvornikov knows the geography and the theater of military operations best,” said Pavel Luzin, an independent Russian military analyst.

The Kremlin might also view him as best-placed to fix the problems the offensive has seen in terms of coordinating its forces, Mr. Luzin said. During military drills in 2020, Gen. Dvornikov oversaw Russia’s much-hyped first use of automated systems for coordinating between various wings of the military, Mr. Luzin said.

In his 2018 essay published in the Military-Industrial Courier, Gen. Dvornikov urged the deployment of coordinated operations—precisely what Russia didn’t do.

“Modern military art and the experience of conducting combat operations in local conflicts of the last quarter of a century show that the creation and use of integrated groupings is becoming increasingly important,” he wrote.

Born in Ussuriysk, a city about 35 miles from both the Russian-Chinese border and the Pacific coast, Gen. Dvornikov graduated from the Suvorov Military School, a local military boarding school for boys. He moved to Moscow to attend college, where he finished the Moscow Higher Military Command School, in 1982.

Russian Army Gen. Aleksandr Dvornikov won battlefield experience as commander of a motorized rifle division during the Second Chechen War; Grozny in 2000.

Photo: Antoine GYORI/Sygma via Getty Images

The general’s path to his position was similar to all of Russia’s current military commanders. He rose up through the ranks in the 1980s and began taking on command roles during the next decade. In the 1990s, he commanded a motorized rifle division in Germany before Russia pulled its forces out in 1994. From 2000 to 2003, he won battlefield experience as commander of a motorized rifle division during the Second Chechen War.

“It’s a group of generals with Soviet backgrounds who built their careers during Putin’s 20 years in power,” Mr. Luzin said. “They know how to work on the battlefield but they also know the rules of the bureaucratic game. Their intellectual capabilities should not be exaggerated, especially in an authoritarian system. Even the Soviet Union gave officers more freedom and autonomy on the battlefield.”

Gen Dvornikov continued rising through the ranks before he was sent to Syria in 2015, when Moscow first intervened in the war on the side of President Bashar al-Assad’s regime, helping him suppress the armed rebellion against him.

The general was promoted to Southern Military District chief the next year at the height of the battle for the city of Aleppo, a turning point in the war when Russian and Syrian regime forces retook one of Syria’s largest cities from rebels. Russian President Vladimir Putin that year bestowed him with a Hero of Russia medal.

Russian President Vladimir Putin in 2016 honored Russian Army Gen. Aleksandr Dvornikov, who then had a different rank, for his service in Syria.

Photo: Nikolsky Alexei/TASS/Zuma Press

“He had a lot of experience in setting up Russian command structure and very crucially was the one in command in the early siege of Aleppo, which saw very intensive urban fighting, and was where the Russian military refined its approach,” said Mason Clark, a Russia analyst at the Institute for the Study of War in Washington, a nonpartisan research organization.

The military strategy undertaken by Gen. Dvornikov involved bombings of hospitals, schools and bakeries, attacks on fleeing civilians, and siege tactics, which are designed to depopulate territory and psychologically wear down opposing forces and their supporters, those familiar with the Russian military say. They say Russia is now resorting to similar tactics, bombarding cities and targeting civilians with the aim of compelling a surrender that will allow Russian forces to move into cities.

The siege of Mariupol has drawn comparisons to the approach in Aleppo, where Russian and Syrian regime forces laid siege to 300,000 civilians for five months. In Mariupol, residents have been deprived of running water, electricity, and sufficient food for weeks. Russian forces have hit a hospital, apartment blocks and a theater where more than 1,000 civilians were sheltering.

Russian forces carried out more than 70 confirmed attacks on healthcare facilities in Ukraine since the beginning of the invasion, according to the World Health Organization. In Syria, 930 medical professionals were killed over a decade of war, with the Syrian regime and Russia responsible for 91% of their deaths, according to Physicians for Human Rights, a group that tracks attacks on healthcare.

In 2016, the Russians helped lay siege to Aleppo, and Moscow’s new commander of the Ukraninan invasion was in command in the early days of the siege.

Photo: Ahmed Muhammed Ali/Anadolu Agency/Getty Images

“The pattern is bomb hospitals so they won’t have access to healthcare so they will be displaced. So the purpose of this is to deprive and depopulate these communities,” said Zaher Sahloul, a Syrian-American doctor who worked providing medical aid in Syria and who recently returned from a relief mission to Ukraine.

Russia’s invasion of Ukraine is a much larger and more costly operation than its intervention in Syria. In its full-scale attack on the largest country by land area in Europe, Russia has committed 150,000 troops, according to Western intelligence assessments. By contrast, the Syrian intervention was much smaller, relying largely on air power to support Syrian government troops and their allied militias on the ground.

Gen Dvornikov is also facing an age-old problem for the Russian military, said Mr. Luzin, the independent Russian analyst.

“The main problem for Russian forces has always been effective management. In this war it was the same thing, in recent wars, and in Soviet wars,” Mr. Luzin said. “He has to solve this problem.”

Write to Evan Gershkovich at evan.gershkovich@wsj.com and Jared Malsin at jared.malsin@wsj.com