The United States border control has been employing a drug traffic fighting aircraft, known as their “Eye In The Sky”. The tethered balloon allows authorities to get a closer view of what’s going on close to the ground as opposed to a typical satellite image that can be tricked from far away.
“The Tethered Aerostat Radar System, or T.A.R.S., monitors the entire border. Six blimps, from Arizona to Texas, carry specialized radar that can detect aircraft flying too low for conventional radar to detect. That includes drones and homemade low flying planes which are equipped with drop baskets…” [ Read more here ]