(Bloomberg) -- Russia is preparing to enlist more contract soldiers as it presses its invasion of Ukraine, aiming to avoid at least for now another mass call-up that could undermine popular support for the war.

The Kremlin is anxious not to repeat the September 2022 mobilization, which shook public confidence and triggered an exodus of as many as a million Russians from the country, three people informed about discussions on the matter said.

With as many as 30,000 new recruits a month, Russia could reinforce army ranks by 300,000 this year, said Ruslan Pukhov, head of the Moscow-based Centre for Analysis of Strategies and Technologies think tank. 

Bolstered by its advantage in ammunition, the Russian army is continuing to advance as Ukraine’s forces struggle because of delays in US and European military aid and personnel shortages. To be sure, relying on a gradual influx of new troops to replace losses and build up numerical strength rather than simply calling up another 300,000 in one go limits Russia’s military options. 

Gaining control of Kharkiv, Ukraine’s second-largest city, or capturing Zaporizhzhia in the southeast would likely require a major new fighting force. An assault on the strategic southern port city of Odesa would be an even tougher goal.

Still, concerns are mounting that Russia may make major gains in the coming weeks by punching through overstretched Ukrainian lines, people familiar with the matter in the US and Europe said. Russian troops are at the outskirts of their next key target in the eastern Donetsk region, Chasiv Yar, whose elevated position makes it crucial to Ukraine’s defense of the area. 

Ukraine at the same time is facing a daily barrage of missiles, drones and bombs that is knocking out important power infrastructure because of a lack of air defenses and hitting army positions. Looking to also bolster their frontlines, lawmakers in Kyiv approved a watered-down version of controversial legislation to recruit more troops.

Russia has detailed plans to expand its armed forces to 1.5 million people from 1.15 million now, of which 650,000 have had combat experience in Ukraine, Defense Minister Sergei Shoigu said in December. In January, Ukrainian President Volodymyr Zelenskiy said Kyiv’s forces numbered just short of 900,000.

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“The shape of the Russian offensive that’s going to come is pretty clear,” the former commander of the UK’s Joint Forces Command, General Sir Richard Barrons, told the BBC. “We are seeing Russia batter away at the front line, employing a five-to-one advantage in artillery, ammunition, and a surplus of people reinforced by the use of newish weapons.”

The Russian Defense Ministry on April 3 said more than 100,000 new recruits had signed up so far this year, with as many as 1,700 people volunteering a day.

Russia’s using generous financial incentives to attract people to the war. Since the beginning of the year, regional payouts to new contract soldiers have increased 40% to an average 470,000 rubles (around $5,000), according to calculations by Re: Russia, a Vienna-based research group set up by former government adviser Kirill Rogov. That’s in addition to a flat rate federal payment of 195,000 rubles.

“The Russian authorities are trying not to carry out a new mobilization, as long as they have the opportunity to avoid it,” said Pavel Luzin, a Russian military expert who’s a senior fellow at the Jamestown Foundation.

Ultimately, any call-up would be President Vladimir Putin’s decision, and the Russian leader has stoked speculation the Kremlin is preparing the ground for a potential next mobilization of reservists by accusing Ukraine without evidence of involvement in the Moscow concert hall attack last month that killed more than 140 people, even as Islamic State claimed responsibility.

For now, the army command is in part relying on getting some current conscripts to sign contracts, according to two people familiar with the situation. This spring, 150,000 Russians will be drafted for standard military service. 

The law allows those conscripts to be sent to the battlefield after four months of military service, said Luzin. 

However, that would violate repeated public pledges not to deploy conscripts to the war zone, so army officials are pushing them to switch to a professional contract, which they can do from the first day of their service under legislative changes approved last year.

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“Everything happens on an absolutely transparent and voluntary basis,” Andrei Kartapolov, a former deputy defense minister who’s head of the lower chamber of parliament’s defense committee, told RTVI channel.  

In fact, an increasing number of draftees are complaining of significant psychological and in some cases physical pressure, according to Idite Lesom, or Get Lost, a non-government organization that helps people who want to avoid being sent to fight in Ukraine.

“They put one boy into a pit and kept him there for several days without food until he agreed to sign a contract,” said the group’s head Grigory Sverdlin. The contracts are officially for one year, but can only be revoked by the Defense Ministry during wartime mobilization, so they’re effectively permanent until the conflict ends, he said. 

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So far, Russia’s approach appears to be working. 

“For the current strategy of inflicting ‘a thousand cuts’ and broad pressure on Ukraine along the entire front, the available manpower and its replenishment through contract recruitment is apparently enough,” said Pukhov, from the Centre for Analysis of Strategies and Technologies.

Russia probably can’t consolidate control over eastern Ukraine by taking the well-defended cities of Slovyansk and Kramatorsk this year, he said. 

Still, Putin’s goal is to have the West reach the “conclusion that Russia prevailing in Ukraine is inevitable and that we must stay on the sidelines,” said Nataliya Bugayova, a non-resident fellow at the Washington-based Institute for the Study of War.  

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