Donald Trump's promise to build a wall between the border of the United States and Mexico is just one option when it comes to border security, NBC News reported.
Around the world, physical barriers aren't the only things countries are doing to keep people out. Border agencies in conjunction with security companies are developing technology, such as "intelligent fences" that can detect intruders. Other options include ground sensors and high-range security camera that can see up to 15 miles away. Sniffer dogs are also being used.
In Europe especially, maritime surveillance is a large share of the market as well, driven by demand for unarmed drones, helicopters and patrol vessels to keep track of the number migrants crossing the Mediterranean Sea. Rather than aggressive tactics, countries are using equipment that is security based.