Glow-in-the-dark stars twinkling in his childhood bedroom and science fiction books in his lap, Shayan Shirshekar grew up fascinated by space. When he was old enough to say what he wanted to be when he was older, his answer was always immediate: an astronaut.

Like many with such aspirations, Shirshekar dreamed of a future working at NASA or a private U.S. space company. It was the gold standard, he thought, something to strive for.

There was one snag, though: Shirshekar grew up at what for him was the unlucky side of Lake Ontario, in Toronto, an hour’s drive from the U.S. border.

That distance is important when it comes to the stringent U.S. regulations that govern the space industry. It’s the roadblock to Shirshekar, 30, and other international students who come to the country to study space, only to find that they’ll be hard-pressed to get jobs when they graduate.

A year and a half from graduation, despite good grades and a job at the Aldrin Space Institute, run by former astronaut Buzz Aldrin’s son Andy, Shirshekar has no job prospects.

“I was trying to follow my passion and look where that’s led me,” Shirshekar said.

Since the International Traffic in Arms Regulation (ITAR) was enacted in 1976, classifying spacecraft and rockets as military technology, international students have been unable to get jobs in the field. Only “U.S. persons” — in other words, citizens or permanent residents — can work for NASA or major private space companies under ITAR.

The problem, though not new, is perhaps more acute now that the space industry in the U.S. — and particularly Florida’s Space Coast — is flourishing. Companies are scrambling to find qualified employees because of a national shortage in the science, technology, engineering and math fields, the kind of skills that feed the space industry.

“It’s really frustrating,” said Laura Seward Forczyk, owner of space consulting firm Astrolytical and a Florida Tech grad. “These were students who came to the U.S., were trained here. So we spend the resources, the time to train people in highly educated, high in-demand fields, and then they take that and leave.”

Brain drain in the industry has happened before and with dire consequences. Most famously, rocket scientist Qian Xuesen, who immigrated to the U.S. in the 1930s to attend school, went on to become one of the founders of NASA’s famed Jet Propulsion Laboratory. His design for a winged space plane inspired the space shuttle. But in the 1950s, accused of being a communist sympathizer, he was deported to China. He went on to become the most central figure in the rise of the Chinese space program, one of NASA’s major competitors.

For many, ITAR is considered a cornerstone of national security. It’s easy to see why. Rockets share many similarities in structure with missiles. The information on building them, down to the nuts and bolts, becomes something to be protected.

Speaking at the International Astronautical Congress in Mexico in 2016, SpaceX founder Elon Musk, who is South African and immigrated to the U.S. through Canada, said he’d have a more international workforce if not for ITAR restrictions.

Seward Forczyk, who has worked with several international students in the predicament, said she worries that “by limiting our diversity, we are actually limiting our ability to lead.”