 Numerous balloons were shot down or blown off course, and the flights led to many diplomatic protests from the target countries.MiG fighter pilots learned that at sunrise the balloons had dipped into shooting range because the balloons floated to a lower altitude as in the colder night air, the lifting gas cooled and became denser, reducing lift, so the balloons descended to lower altitudes where the air was denser.Authorized by President Dwight D. Eisenhower on December 27, 1955, Project 119L was the first espionage use of the balloons that had been tested in previous projects, such as "Moby Dick High".