Earlier today President Donald Trump repeated his claim that constructing a wall along the U.S.-Mexico border will stop "drugs from pouring into our country and poisoning our youth."

But based on the government's own assessment, the bulk of drugs are smuggled into the country through existing border checkpoints — stowed away in "passenger vehicles or tractor trailers," according to a 2016 report by the Congressional Research Service.

Though it's gamble, traffickers attempt to blend in with travelers crossing the border through legal points of entry. If they're able to avoid detection, traffickers can smuggle greater quantities through vehicles than if they were to cross the border illegally. These images from Customs and Border Protection (CBP) show that it doesn't always work out that way.

"In passenger vehicles, the drugs may be held in secret compartments; while in tractor trailers, the drugs are often co-mingled with other legitimate goods," the congressional report noted. "Less commonly used methods to move drugs include smuggling them through cross-border underground tunnels and on commercial cargo trains, small boats, and ultra-light aircraft."

Because traffickers rely on these methods, experts aren't sure whether a wall will actually deter those who are smuggling drugs —tightening enforcement along the border checkpoints may be more effective and less costly.