Nine American farrier schools are members of an exclusive group. The federal government allows them to teach foreign nationals who obtain student visas. Yet, some inexplicably believe that these educators are nothing more than a risk to national security.

ABC News recently reported that 58,000 foreign nationals remained in the United States after their student visas expired. More than 6,000 of them are considered a “heightened concern” — and the Department of Homeland Security has no idea where they might be.

This isn’t a new problem.

Hani Hanjour entered the U.S.  after acquiring a student visa. On Sept. 11, 2001, the 29-year-old Saudi national flew American Airlines Flight 77 into the Pentagon, claiming 189 lives. Hanjour exploited a yawning gap in our nation’s security by entering the country on the false pretense of gaining an education. Thirteen years after the devastating attacks, it’s a gap that hasn’t been closed.

“It’s shocking to me that someone could get away with failing to report a foreign student who did not show up for school or who left early,” says Kash McAnally, who handles foreign student visas at Oklahoma State Horseshoeing School in Ardmore, Okla. “I have to keep in contact with the federal government throughout the entire process. If a student doesn’t show up, then I notify the government.”

It’s a detailed and strict process. When a foreign student wishes to gain an education in the U.S., the school must enter their information in a computer database and provide the appropriate paperwork. The student must validate the visa online and pay the fees involved. The student must present the paperwork to federal officers at the border before being permitted into the country. School officials must notify the government whether the student arrives and leaves.

Some students fall through the cracks.

“They just disappear,” Coburn told ABC News. “They get the visas and they disappear.”

While that might be true of larger schools, it’s difficult to lose students when class sizes are so small.

“A school like mine has a population of less than 30, so we get to intimately know these students,” explains Chris Gregory, owner of Heartland Horseshoeing School in Lamar, Mo. “Any school with a small population means that students are known as a person and not a number. It’s easier to get lost in the numbers than it is as an individual.”

With more than 9,000 schools that are authorized by the U.S. government to educate foreign students, how can nine farrier schools pose a national security risk?

“We know we have a lot of non-accredited universities that are using this system to bring people in, collect money, and not educate them at all,” Sen. Tom Coburn, an Oklahoma Republican, told ABC News. “To me, it’s a mess.”

It might be a mess, but the vast majority of foreign students who attend Oklahoma State Horseshoeing School and Heartland Horseshoeing School are Canadians. In fact, not once have students from nations hostile to the U.S. attended these two schools.

“We bring foreign people here and not only teach them to help horses in their country, but we bring their money here and we send a lot of our values back to their countries,” Gregory says. “They don’t just become my students. They become my friends and most of them end up with a very favorable impression of America.”

On the heels of ABC’s report, Sen. Charles Grassley, R-Iowa, introduced legislation that would require schools to be accredited before accepting foreign students. While accredited institutions such as Oklahoma State Horseshoeing School and Kentucky Horseshoeing School will not be affected if the legislation passes, it could have serious implications for those that are not.

“My population for the year might be 45 students,” says Gregory, whose school is not accredited. “If only 10 of those are from foreign countries, then it would take a lot of resources to become accredited for such a small number. If these terrorists are scaring people so badly that we resort to this type of legislation, then the terrorists are winning.”

In the meantime, the ABC News report could have a ripple effect on the reputation of horseshoeing schools.

“It’s like we’re guilty until proven innocent,” McAnally says. “People who are close to me know it’s not true, but there are a lot of people who didn’t even know horseshoeing schools existed until they saw that report.”