FACTBOX: Five facts about NATO commander Stanley McChrystal

(Reuters) - The top U.S. and NATO commander in Afghanistan, Stanley McChrystal, testifies to Congress starting on Tuesday about the way ahead in Afghanistan following a decision to send in 30,000 additional U.S. forces.

Here are five facts about McChrystal:

* Stanley McChrystal, a four-star general, took over command of U.S. and NATO forces in June and in August issued a bleak assessment of Afghanistan, warning that the mission would fail without new troops. That classified assessment was leaked to the media in September.

* McChrystal was formerly chief of the U.S. military's Joint Special Operations Command, the most elite and secretive branch of its special forces. It consists of the Army Delta Force and Navy Seal units tasked with hunting down "high value targets" in Iraq and Afghanistan. Targets included Abu Musab al-Zarqawi, an Iraqi insurgency leader killed in a 2006 U.S. air strike.

* McChrystal, who comes from a military family, is described as a workaholic who sleeps just four or five hours a night, eats infrequently and is avid reader and runner.

* He graduated in 1976 from the U.S. military academy at West Point, where President Barack Obama announced his decision to deploy more forces. McChrystal met Obama on Air Force One in Copenhagen in October for their first face-to-face talks since presenting his grim assessment.

* McChrystal was linked to a scandal over a posthumous Silver Star awarded to famous American football player Pat Tillman, whose death by friendly fire in Afghanistan was initially portrayed as death by enemy fire. An investigation cleared McChrystal, who approved the medal, of any wrongdoing.

(Reporting by Phil Stewart in Washington; Editing by Chris Wilson)