The US military hasn’t completely abandoned experimental (and classified) missions, as evidenced by the announced April 19 launch of the X-37B, an orbital test vehicle.  The vehicle appears to be a winged reusable vehicle with traditional landing gear.  Commentators are somewhat confused as to its ultimate purpose, lending support to the theories it will support classified missions, as well as a variety of Air Force experimental operations.

The X-37B has been in development for years (and was even originally scheduled for a 2008 launch).  Various reports indicated that the unmanned vehicle might be intended to stay in orbit for up to 9 months before conducting its own re-entry and landing.