It took these two alleged drug smugglers 15 seconds to scale the U.S-Mexico border fence

Here’s all the evidence you need to prove that Donald Trump’s border wall, no matter how high it’s built, won’t be able to stop people from sneaking into the United States.

A Mexican journalist taping a report on the border last Wednesday inadvertently generated some breaking news when her TV Azteca cameraman spotted two alleged drug smugglers scaling the 20-foot-plus border fence and dropping into Nogales, Arizona.

The young men, wearing homemade backpacks and carrying cellphones, climbed the fence in plain daylight with the nimbleness of two guys who have had plenty of practice. Once they noticed they were being filmed, the two men climbed back up and over the fence and returned to Mexico. The second cross-border stunt took 15 seconds.

A border patrol squad car was parked nearby.

Although the footage could be used to make a case for more efficient border policing, it also shows how ineffective a wall is at stopping determined drug smugglers. Those who don’t go over go under, as evidenced by dozens of so-called narco-tunnels that have been discovered along the U.S.-Mexico border in recent years.

Cost-effectiveness is also an issue. In 2009 a U.S. government audit revealed that border fencing cost more than $2 billion, and warned the price tag would continue to increase due to reparations and maintenance. Last year, the U.S. government spent more than $700,000 to repair part of the fence along the Nogales, Arizona borderline, after it got knocked out by a rainstorm.

A 2013 report by the Pew Research Center found most undocumented immigrants don’t even bother with the fence at all; they enter the U.S. legally and simply overstay their visas.