German airship developer CargoLifter AG and aerospace giant Boeing Co. said Thursday they have agreed to explore the development of sophisticated, high-altitude blimps for use in U.S. homeland security defenses.

CargoLifter’s head of corporate development, Christian von Tuempling, said working groups will study potential uses of lighter-than-air craft by military and commercial customers, with a “special focus on homeland defense.”

One possibility, he said, would be large airships equipped with special sensors stationed at altitudes as high as 66,000 feet for surveillance purposes.