VIENNA — Mahmoud was not looking forward to the end of his university education in Syria. School had been tough, sure, but the military would be a lot tougher, and he knew he could be forced into service defending the embattled Bashar al-Assad dictatorship against a bewildering array of rebels, including the so-called Islamic State. So Mahmoud decided to get out of the country.

“You can’t say no; you must be in the military,” says Mahmoud, who, like many Syrian refugees, does not want to use his last name for fear authorities will go after his relatives still in the country. “It’s the military or prison.”

Mahmoud, 24, eventually arrived at the train station here in Vienna, hoping to go on to Germany or Sweden to continue university and eventually bring over his family left behind in Syria.

In Mahmoud’s hometown of Damascus, there are authorities on every few streets who will stop men as they pass by and ask for their identity cards. They will also go into people’s homes looking for young men to take into the military. And once they’ve got you, they don’t let you go. Mahmoud says his friend who has been in the military for four years has no chance of ever leaving the country.

“Every week, every month, we don’t know when they are coming,” he said. “All the time we must be careful.”

Mahmoud shows his ID card and points out his birth date. He’s a prime age for service. But as a student, in the past, he could present his university papers to authorities and not be taken.

Andrew Tabler, an expert on Syria at The Washington Institute, says President Bashar al-Assad ramped up his drive for conscription last year. “They were only partly successful,” he says. “So it’s been tough [for the regime]. Their numbers aren’t what they used to be.”

By some estimates the number of fighters in Assad’s military has dropped from 350,000 to about 200,000 since the conflict started four years ago. Over 80,000 soldiers and pro-government militiamen are believed to have been killed, representing more than a third of those who have died in the war, according to the Syrian Observatory for Human Rights. And there are at least 70,000 men who have dodged compulsory military conscription, the Observatory says.

A major problem for Assad is the increasing difficulty getting members of his Alawite sect to join the army’s ranks, where they have long been the core of his security apparatus. So he has been forced to turn to the majority Sunni population for more and more recruits, but they often are reluctant and potentially unreliable soldiers for the regime, since virtually all the opposition forces are Sunni as well.

In a bid to boost numbers, Assad announced in July that draft dodgers and deserters both inside and outside of the country would be given amnesty. In the same month, a public campaign was held encouraging men to join the army.

Jamal, 42, who is also stuck at the Vienna train station waiting to go abroad, says he was a high-ranking officer in the military for 20 years.

He says the regime would give soldiers a five-month advance on their salaries.

Andrew Tabler says Assad seems to have failed to increase numbers. One indication is a string of failures on the battlefield, and the huge push to get more cannon fodder. They other is the extent to which draft-dodging has helped fuel the refugee crisis as men try to escape conscription.

“The pressure he has put on everyday Syrians,” says Tabler, “is one of the reasons they have gone to Europe to seek refuge.”

Rami, 30, is one of those. Lying on the floor of the train station in a gray-and-black knitted hat, with a coat covering his legs, he says he first left Syria for Lebanon for what he thought would be a temporary respite.

Then his parents told him a letter came for him for military service. Knowing authorities could take him away at any time if he went back to his country, he decided to leave the region permanently.

“Some people can’t run away,” he said. “Some were forced.” And he didn’t intend to be one of them. He wanted to be able to care for his children, something he could not do if he died fighting.

There were also moral reasons for not wanting to fight for Assad, he said. “Maybe I will kill somebody who is innocent,” he said, “Because I don’t know who my enemy is. If I’m in the military I must kill the people… women, children … you must kill these people.”