Iran’s attempt to control al-Qaeda may be one of the biggest strategic benefits the rogue state has ever enjoyed. And it could cost the United States dearly if Joe Biden is not careful. The death of al-Qaeda’s longtime leader, Ayman al-Zawahiri, proves how dangerous it is to lead the world’s most notorious Islamist terrorist organization. Given the group’s international reach and the fact that it has survived nearly 30 years of conflict with America’s war machine, many observers have been surprised by the fact that al-Qaeda did not have a succession plan in place. This is especially odd considering how...