U.S. military special forces and the Customs and Border Protection agency recently finished testing border wall prototypes — and the results couldn't be more conclusive.

What did they find?

According to the Associated Press, the commandos and CBP finished a three-week test this week and found the new walls "should stop border crossers."

Commandos and agents attempted "to breach and scale the eight models in San Diego, using jackhammers, saws, torches and other tools and climbing devices" but were unable to breach the walls each time, a U.S. official anonymously told the AP.

The testing was conducted on eight different wall proposals and was designed to identify the strengths and weaknesses of each design. The best design, the officials concluded, was a see-through steel barrier topped by concrete. The government prefers this design because it allows agents to see through the wall at ground level, while the concrete at the top makes scaling the wall exponentially more difficult.

However, officials also believe pulling the strengths from each design will help produce the best final product.

More details from the report:

The prototypes are 18-30 feet tall and were built last fall by multiple contractors, who were awarded between $300,000 and $500,000 for each prototype.

The "highly trained testers" were able to scale 16-20 feet, but needed help after that. But even if they were able to scale the wall, the testers said they had serious safety concerns descending from the 30-foot height.

One tester was able to land a metal hook on the top of the wall without help. However, tubes at the top of the prototypes would thwart such a scaling technique, according to the AP.

The CBP is still in the "testing phase," according to the AP, and will continue to evaluate results. Meanwhile, President Donald Trump is insistent that a wall covering the complete southern border must be build to protect America and its interests.