Lycra-clad bodiessprawled on the floor of a Moscow fitness center while masked police in riot gear strode among them checking identity papers and migration status.

The March 31 raid ended with immigrants being rounded up and taken to a military recruitment office.

The raid -- one of several across Russia in recent weeks was the latest evidence of how authorities are seeking new soldiers for Ukraine, where Russias all-out invasion is now its fourth year.

It also coincided with the annual springtime draft of conscripts, who are by law barred from combat duties or foreign deployment.

Taken together, the moves show how Russias military is seeking to increasethe overall size of its armed forceswhile at the same time making sure it has the manpower to continue grinding down Ukrainian troops.

Russia has been secretive about the number of casualties it has suffered since launching its full-scale invasion in February 2022. Western estimates say the number of Russian killed and wounded exceeds700,000-- more than all wars Moscow has fought combined since World War II.

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Filling the ranks

In September 2022, as Russian forces bogged down in Ukraine, President Vladimir Putin ordered a partial mobilization of hundreds of thousands of men -- mainly reservists -- in a bid to replenish troop strength. It was a deeply unpopular move.

Officials have since turned to other methods to keep up troop strength, including paying extraordinarily high wages and benefits to volunteers, who are known as kontraktniki. Widows and survivors also receive covetedsocial benefits.

Theyve also targeted migrant workers in Russia in raids not only on fitness centers, but alsowholesale markets and construction sites.

Some are seasonal workers who are tricked into signing contracts to fight; others are migrants who obtain Russian citizenship but fail to register with the national draft system.

The spring conscription is part of the twice-a-year conscription process under Russian law, which requires all men between 18-30 to serve in the military. The order signed on March 31 by Putin aims for 160,000 conscripts, which is well above previous recruitment targets.

Russian President Vladimir Putin at the Kremlin in Moscow, Monday, March 31.

Modernizing the army

Since the February 2022 invasion, authorities have also sought to modernize the Soviet-era system for identifying men -- conscripts and reservists alike -- for recruitment or drafting.

Officials have created anelectronic systemof notification and registrations to cut back on draft dodging as well.

Theyll use various methods to reach this number, said Ivan Chuvilyayev, from a nongovernment organization called Go By The Forest, which helps Russians being drafted.

Theyll do everything theyve done so far: raids in all sorts of places, including coming to peoples home addresses and forcing entry, tracking them down, waiting for them outside their apartments, he toldCurrent Time.

The new system also includes something called the Unified Draft Center, or EPP, which is supposed to speed up the processing of recruits -- and reduce the ability of people to file legal or administrative appeals or exemptions.

Theres a raid, they take the person to the EPP, and do the paperwork very quickly, within 5-10 minutes before sending him to a military unit, Chuvilyayev said. Its done so that the whole time hes at the EPP he cant speak to anyone, cant call anyone, cant reach family members.

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At present, theres only one EPP, in Moscow, but others across Russia may follow. TheDefense Ministrysays it speeds up and simplifies recruitment, offering comfortable waiting rooms and no queues.

They file complaints, often repeatedly, not to defend their rights, but to evade military service,Andrei Kartapolov, a former military officer who serves on the defense committee in the lower house of parliament, said during a debate in February on a bill to tighten conscription rules.

He said there were around 5,000 such complaints in each draft.

No sick notes accepted

Russian recruitment offices were also not accepting medical conditions which would normally exempt people from military service, Chuvilyayev said. He said he expected new EPPs would increase this practice.

At the EPP these diagnoses and the papers relating to them will be swept under the carpet. The commissions will ignore them. The military enlistment offices already loved losing, forgetting, and ignoring them, he said.

Though conscripts are legally barred from being sent to combat, recruiters are known to have coerced or threatened conscripts before the conclusion of their service into signing contracts to fight in Ukraine.

"Most of the time they have no access to lawyers or human rights organizations; they simply have no choice,"Artyom Klyga, a lawyer with the Movement of Conscientious Objectors, told RFE/RL last month.

Russian law bars kontraktniki from resigning from service until the Kremlin declares an end to the conflict.

There are also reports of conscripts being killed inKursk, the Russian region that Ukrainian troops invaded last August but have since been all but pushed out of.