Al-Golani’s ties to al-Qaida stretch back to 2003 when he joined extremists battling U.S. troops in Iraq. The native of Syria was detained several times by the U.S. military, but remained in Iraq. During that time, al-Qaida usurped likeminded groups and formed the extremist Islamic State of Iraq, led by Abu Bakr al-Baghdadi. In 2011, a popular uprising against Syria's Assad triggered a brutal government crackdown and led to all-out war. Al-Golani's prominence grew when al-Baghdadi sent him to Syria to establish a branch of al-Qaida called the Nusra Front. The United States labeled the new group as a terrorist...