A technical glitch and then a weather problem prevented the Army from firing its laser, known by the acronym MIRACL, at an Air Force satellite in orbit.
It was to have been the first known offensive use of a laser against a satellite.
The Pentagon had planned to zap the satellite in an experiment designed to test the vulnerability of satellites to laser attacks.
Navy Capt. Michael Doubleday, a Pentagon spokesman, said Tuesday a technical difficulty forced the Army to scratch its first attempt Saturday. The laser was to shoot bursts of concentrated light from White Sands Missile Range, N.M., to an aging satellite 260 miles from Earth.
The next attempt, Monday night, was scratched because of excessive cloud cover.
It now appears unlikely the test will happen. Doubleday said the satellite is not in the right position in orbit and it is quickly losing power because its batteries are running low.
