Russia is depopulating parts of eastern Ukraine, forcibly removing thousands into remote parts of Russia

(CNN) — Hundreds of thousands of Ukrainians have been processed through a series of Russian “filtration camps” in Eastern Ukraine and sent into Russia as part of a systemized program of forced removal, according to four sources familiar with the latest Western intelligence — an estimate far higher than US officials have publicly disclosed.

After being detained in camps operated by Russian intelligence officials, many Ukrainians are then forcibly relocated to economically depressed areas in Russia, in some cases thousands of miles from their homes, and often left with no means of returning, sources said.

Although some Ukrainians have voluntarily entered filtration camps to try to escape the fighting by entering Russia, many have been picked up against their will at check points and in bomb shelters. After spending an average of around three weeks at the camps — where sources and eyewitnesses say they are held in inhuman conditions, interrogated and sometimes tortured — some are sent across the border into Russia and given state documentation.

From checkpoints in Rostov and other Russian towns, many Ukrainians are then relocated to far-flung corners across Russia, the sources said. In some cases, Ukrainians have been sent to Sakhalin Island, a distant spit in the Pacific Ocean on Russia’s far east — 10,000 miles from the Ukrainian border. If they are fortunate, sources tell CNN, Russia will provide housing in residential areas and perhaps a Russian SIM card and a small amount of money.

Others are simply dropped off with nothing and expected to survive on their own. Still other Ukrainians are stuck in filtration camps inside Russia, close to their own homes, with no way to leave, other sources added.

Taken together, western intelligence reporting described by CNN sources offers new details that go beyond scattered eyewitness accounts from the region and paints a disturbing picture of a comprehensive resettlement process.

Claims of cultural genocide

It’s all part of Russia’s effort to cement political control over occupied areas, sources say — in part by eliminating Ukrainians believed to be sympathetic to Kyiv and in part by diminishing the Ukrainian national identity through depopulation and what some human rights activists term “cultural genocide.” It’s an indiscriminate system that Russia has employed before, notably during both Chechen wars.

Intelligence officials believe all Ukrainians entering Russia are being processed through these filtration camps. Top US diplomats have already publicly condemned the practice and said these actions constitute war crimes.

“Ukrainians do not necessarily have to be thrown on a back of a truck but many are put in a situation where they don’t have a choice: You get on the bus and go to filtration and then to Russia or you die in the shelling,” said Tanya Lokshina, Europe and Central Asia associate director for Human Rights Watch. “These are forced transfers forbidden under the laws of war.”

Russia’s Ministry of Defense did not respond to requests for comment.

It’s difficult to confirm precise numbers, and officially, Western estimates vary from tens of thousands to 1 million people.

But even the more conservative estimates hint at a massive program of forced dislocation on a staggering scale. And even as US officials have publicly cited much lower numbers, the sources say that in reality, it’s clear that at least hundreds of thousands of people have been pushed through the camp system and sent to Russia.

Late last week, Russian Defense Minister Sergei Shoigu said Russian armed forces are “doing everything to prevent deaths among the civilian population. Since the beginning of the special military operation, more than 1.37 million people have been evacuated from the dangerous regions of the people’s republic, as well as from Ukraine to Russia.”

Camps run by Russian intelligence

The camps and the processing centers inside Russia are largely run by the FSB, the Russian intelligence agency responsible for Moscow’s operations in Ukraine, according to three sources familiar with western and US intelligence. Before Russia invaded Ukraine, western intelligence had assessed that the agency had plans to establish and operate a filtration camp system to kill politically undesirable Ukrainians and ship the rest to Russia, according to two sources familiar with the assessments.

The human toll of Russia’s strategy is incalculable. Conditions at the camps are appalling, sources and eyewitnesses say. CNN earlier this week reported eyewitness accounts of beatings, dehumanizing and invasive identity checks, and a lack of sanitary facilities in ad hoc facilities, which are set up in tent camps, schools and hospitals. There has been a tuberculosis outbreak at one camp, while at another, Ukrainians have died from lack of medical care, according to a source familiar with western intelligence.

Those who survive the filtration process and are scattered across Russia face an odyssean journey to return home. Some have been able to make their way across the border into Georgia, Belarus or Estonia. But still others are likely stuck, thousands of miles from home with no passport, no financial resources, and few options, sources say.

“This way they are sure not to cause any problems [for Russia],” said one of the sources. “If they have money or access, they can probably catch a flight to Georgia. But that’ll be far and few between — they couldn’t afford to leave [Ukraine] in the first place, so that tells you something.”

According to one source familiar with western intelligence, the majority of Ukrainians who are being sent across the border are women, children and the elderly.

But not all Ukrainians who go through the filtration process in occupied Ukraine are sent to Russia.

Some disappear without a trace. Still others languish in the camps in Ukrainian territory, according to a report that Human Rights Watch is in the process of assembling.

Survivors of Mariupol

Lokshina, the Human Rights Watch official, said hundreds of Ukrainian men were taken from Mariupol and have been held in two eastern Ukrainian towns, Bezimenne and Kazatsoe. Some have been there for more than a month, held in school buildings and a local event hall.

“They were told they would be able to leave in 2 to 4 days, once they clear filtration, but their passports were not returned to them. So even though they are not under lock and key, they cannot leave. Without their passports it would be simply suicidal,” Lokshina said. “They are given no clarity as to their prospects and the purpose of their protracted detention.”

Just this week the Ukrainians in Kazatsoe were given back their passports and allowed to leave, but the Ukrainians in Bezimenne are still there. Their fate is unknown.

Detained Ukrainians are able to use their cell phones when they get Wi-Fi, she said. But they also have to be careful about what is on their phones because the devices are taken by Russian troops and plugged into computers that takes and appears to store their data — a complete violation of privacy, Lokshina said.

“They are fearful that so-called DNR will forcibly draft them to serve in their armed forces,” she said, using an acronym to refer to the self-proclaimed breakaway eastern territory of the Donetsk People’s Republic.