When Alexander was due to finish his year of mandatory military service in October, his commander told him he had no choice: He had to sign a contract to extend his stay in the army and head to southern Russia for troop exercises.

The 20-year-old knew that meant he might end up fighting alongside pro-Russian separatists in eastern Ukraine. Other soldiers he talked to had been sent there.

His commanders "didn't talk about it, but other soldiers told us about it, primarily paratroopers who had been there," Alexander said in an interview with The Associated Press, which is not using his surname for his safety.

The former private first class ended his military service earlier this month. He avoided being sent to Ukraine — although not without first being threatened with prison for desertion.

Human rights groups have received dozens of complaints in the past month alone from Russian conscripts like Alexander who say they have been strong-armed or duped into signing contracts with the military to become professional soldiers, after which they were sent to participate in drills in the southern Rostov region.

"We receive messages from all over in which (soldiers) say that they're being sent again to Rostov for military exercises," said Valentina Melnikova, head of the Committee of Soldiers' Mothers, a group with a three-decade history of working to protect soldiers' rights.

"Those who have been there (to the Rostov region) before know that in actual fact it means Ukraine."

Because only contract soldiers can legally be dispatched abroad, worries are spreading among families that inexperienced young conscripts could be sent to fight in eastern Ukraine.

While Russia has denied it is sending arms and troops to support the separatists, since the summer dozens of soldiers have been reported killed by explosions during drills in the Rostov region — deaths that rights groups actually attribute to the conflict over the border in Ukraine. Weapons appear to flow freely across the frontier, and one group of Russian paratroopers was even captured in August, 50 kilometers (30 miles) inside the war zone.

So far, the Russian government has been able to keep a tight lid on information about any soldiers in eastern Ukraine through a shroud of official denials, harassment of independent reporters who cover the deaths, and carrot-and-stick pressure on the families of those killed. But rising concerns among families with young sons could pose a risk for President Vladimir Putin.

Russia's secrecy about the soldiers' deaths has an important precedent: During the Soviet intervention in Afghanistan in the 1980s, the government released little information about those killed in the conflict. When the true numbers of casualties became known, the intervention turned unpopular.

More than 5,600 people have been killed since April in the fighting between Ukrainian troops and the rebels. It is unclear how many Russian soldiers have died in the conflict, as the Defense Ministry has rejected rights groups' requests on the number of soldiers killed on duty in 2014. But the rising casualty count among Russian soldiers specifically could prove decisive in Putin's thinking as he comes under pressure to prevent an expansion of the conflict that might put more Russians in the line of fire.

"This is a conflict that reaches pretty deep into the psyche of the Russian people. It's not a foreign conflict. ... It's something very close to home," said Dmitri Trenin, an analyst at the Carnegie Endowment in Moscow. "This is something that's at the back of a lot of people's minds, and in particular, people with sons of draft age are worried.

"Military conquest, in my view, would not be supported by the Russian people, and I think everyone knows it," he added.

In October, Alexander was preparing to return to his hometown of Inta, a city of 30,000 people that skirts the Arctic Circle, when he and a dozen other recruits were told to report immediately to their base outside of Moscow.

"They told us: You have to go on a trip," he said as he wolfed down a full tray of food at the local McDonald's. "At first there wasn't any talk about a contract, but later they said that in order to go on the trip we would have to sign a contract, because we can't go as conscripts."

Russia requires almost all young men to serve in the army for one year at age 18, although many find ways to defer or avoid it. Those who want to have careers in the army can become professional soldiers by signing contracts for two or three years.

Alexander and his best friend in the unit both have pregnant girlfriends and had no intention of extending their army service. But they were told that they had already agreed to the trip, and that they couldn't back out.

"We wanted to refuse," he said. "But they refused our refusal, and we had to go."

The commander assured them the contract was a formality and they could quit within a month, when the trip was over. But Alexander had different commanders in Rostov, who told him that he was obliged to carry out his three-year contract. He heard tales of fighting from more experienced soldiers who had already been to Ukraine. Alexander would not repeat those stories, noting that he "did not want to go to jail" for revealing state secrets.

The Russian Defense Ministry did not respond to a written request for comment sent Feb. 9 or to follow-up phone calls.

Adelya Kamelatdinova's 19-year-old son was serving as a recruit in the army in July when he sent her a text message saying he was being sent to military exercises in Rostov. Then in August, he disappeared for weeks — only to resurface in September and tell her had been stationed in the Ukrainian region of Luhansk, in a village about 80 kilometers (50 miles) from the Russian border.

When she went to the local recruitment office to complain with another mother whose son had been hospitalized with a concussion, nobody listened: "They told us that our sons were participating in exercises and there aren't any soldiers in Ukraine; that it was a fantasy we thought up."

Kamelatdinova, who asked that her son's name not be used for fear of retribution, said he had not signed a contract but that he had been forced to sign a statement in which he agreed to cross the Ukrainian border. The document did not have a specific date on it listing the span of the assignment.

Melnikova, from the Committee of Soldiers' Mothers, believes the drive to recruit more professional soldiers could be a way to make Russia's involvement in the conflict look retroactively legal, were it ever to become public. Rebel leaders have also said that any Russian soldiers in eastern Ukraine are volunteers fighting during their vacation time — a privilege enjoyed by contract soldiers alone.

"Here they got some smart-aleck lawyers who said, 'OK, we'll observe at least this (law), we won't send conscripts,'" she said. "It's absurd and nonetheless illegal."

The recruits are sometimes tempted by the promise of relative fortunes — a minimum of 20,000 rubles ($300) per month, compared with the 2,000 rubles ($30) that conscripts usually receive. But often they say they are tricked, told that the contract will only last for one or two months, or threatened.

"My son said they held them all in an auditorium, threatened that they would ruin their reputations, send them crawling through the trenches ... and told them they were traitors of their country," said the mother of one soldier who serves at a military base in Kamenka, about 100 kilometers (60 miles) northwest of St. Petersburg. She asked that neither her name nor that of her son be used for fear of reprisals.

"A lot of them gave in, whoever's nerves didn't hold out," said the woman. She added that her son had managed to turn down the contract, but that many of his fellow conscripts hadn't, and were supposed to leave for Rostov this week.

Many conscripts who then try to break the contracts are threatened by commanders with being considered absent without leave, a charge punishable by up to five years in prison.

Alexander and his friend ultimately fled Rostov on Dec. 31. They said they were threatened with desertion by their commander in Naro-Fominsk, and it was only after reaching out to NGOs for legal help that they were able to return to Naro-Fominsk to legally quit. But most conscripts are 18 or 19 and have little awareness of their rights to do so: Alexander says that the 10 other conscripts from his division sent to Rostov with him in October are still there, and that he has heard from other soldiers that 500 new recruits signed contracts in January, and were also headed there.

"The phrase 'I'll put you in military prison if you don't sign the contract' explains everything," said Alexander, when asked why he and so many other conscripts collapsed under the pressure.

Irina, the mother of a 19-year-old recruit serving in the Nizhny Novgorod region who asked that her last name not be used for fear of reprisal, said her son had recently called to say he had signed a contract and was on his way to Rostov. She didn't know whether he had been coerced or not, but said she had never heard him previously mention plans to sign a contract.

"I deceive myself and tell myself that it's just the army, that everything has to be this way, that everything is OK," she told the AP. "But they've sent them for three months to the border with Ukraine. ... Of course I'm scared."