How Smugglers Get Drugs and Other Contraband Over the Border

Mexican authorities said on Monday that they had discovered a homemade bazooka that appeared to be designed to launch packages over the border fence from Mexico into the United States.

This makeshift launcher, discovered in the state of Sonora across from Arizona, is the latest in innovative methods used to smuggle drugs and other contraband over the International Boundary Fence into the U.S.

While the bazooka method has been used to throw drugs over a fenced area of the border in the past, it is not common or particularly effective, according to Customs and Border Protection (CBP). A similar contraption was discovered on the California border in 2013.

"As you might guess, someone needs to be reasonably close to the fence to receive the package of drugs where agents patrol. Or come by later to look for it," CBP spokesperson Ralph DeSio said in a statement to ABC News.

Presidential candidate Donald Trump has repeatedly said he would build an extended border wall.

"We will build a great wall along the southern border," said Trump during his immigration policy speech at the end of August.

These methods show that even with a wall, smugglers find new ways to try to get people and things illegally into the U.S.

Another method is to construct a trebuchet, which is similar to a catapult but uses a hinged counterweight or stored energy source instead of a flexible arm. Trebuchets and air cannons are generally seized by authorities in Mexico, said CBP Joint Task Force-West's John Lawson.

The trebuchet seen in the photo below was seized in January 2011 in Naco, Sonora, Mexico. Mexican authorities were testing the capability of the equipment to lob packages when the photo was taken, according to CBP.

Another unusual method is the use of ultralight aircraft, where a couple of hundred pounds of marijuana can be placed in a large basket under the piloted craft and flown over the fence to a predesignated point. The pilot then drops the load for a quick pickup on the north side of the border and returns to Mexico.

"This method can be dangerous for those on the ground and also for the pilots if the basket doesn't release cleanly, making the ultralight unstable resulting in a crash. These ultralights are also as noisy as a large lawnmower and can be heard by agents on the ground, giving them notice of the incursion," DeSio said.

The most common method is by lobbing softball-sized packages of marijuana over the fence, according to CBP. Several "balls" are thrown into a U.S. residential area, such as a backyard, and are retrieved by a co-conspirator, Lawson said.

Smugglers have also constructed cannons that use high-pressure air to launch marijuana over the fence and into an open field, according to CBP. These projectiles can weigh up to 60 pounds.

In 2015, a go-kart was used to smuggle drugs across the Arizona border, according to the CBP. This vehicle which was intercepted by CBP in September 2015.

Smugglers have also tried to drive over the fence, according to the CBP, as seen in this photo.

-Anne Laurent contributed to this story.