An online organization that tracks the crimes of the Lord's Resistance Army says the rebel group is losing fighters through defections encouraged by United States military advisers.

The LRA Crisis Tracker said Monday that at least 19 LRA fighters defected in the last nine months. In the same period a senior rebel commander was captured while another was killed.

The LRA is led by Joseph Kony, a brutal warlord who catapulted to global fame last year when the U.S. charity Invisible Children made a popular online video highlighting his crimes. About 100 U.S. special forces are helping African troops to hunt down Kony. Only about 200 LRA fighters are still active, according to Ugandan officials, but the rebels still abduct civilians in Congo and the Central African Republic.