With the wars in Iraq and Afghanistan ended or winding down, President Obama has been reluctant to engage the United States in direct military action to solve ongoing crises in Syria, Iran and North Korea. Instead, he has pursued diplomacy and international sanctions while holding out the option of using military force. But sanctions do not appear to have convinced Iran or North Korea to discontinue their nuclear programs, which potentially threaten the United States and its allies. In Syria, the United States had resisted arming insurgents trying to overthrow Bashar al-Assad, but reports that Assad has used chemical weapons against his people have forced Obama to change his position. Meanwhile, the president’s growing use of unmanned drone aircraft in the war on terror is raising questions at home.