Beginning in 1908 and lasting until 1937, the U.S. Army established a program to operate airships. With the exceptions of the Italian-built Roma and the Goodyear RS-1, which were both semi-rigid, all Army airships were non-rigid blimps. These airships were used primarily for search and patrol operations in support of coastal fortifications and border patrol. During the 1920s, the Army operated many more blimps than the U.S. Navy. They were also used because they were not seen as "threats".