 Little is known about his life before the age of 20, when he and childhood friend Nawaf al-Hazmi went to Bosnia and Herzegovina to fight with the mujahideen in the Bosnian War.After the war, Mihdhar and Hazmi went to Afghanistan where they fought alongside the Taliban against the Northern Alliance, and al-Qaeda would later dub Hazmi his "second in command".In 1997, Mihdhar told his family that he was leaving to fight in Chechnya, though it is not certain that he actually went to Chechnya.