Just my opinion: Obama intervening to overthrow the Libyan government when we promised to leave them alone if they gave up their nukes was probably the worst foreign policy mistakes since Bush. That kicked off a worldwide nuclear arms race and ensured no dictator would ever again disarm. We will promise not to attack you, and then just do so when we change our minds in a few years.
Also endless bombing throughout the Middle East and assassinating an American citizen abroad without a trial.