Unless nobody told me that the new class of US Destroyers are now equipped with teleportation devices - that makes no sense.
A predator was launched from Italy immediately when the crowd started gathering, before the attack was even declared - went full speed across the Med - and arrived during the attack.
An army commando unit was in the air during the attack but they weren't expected until the next morning, and turned around once everyone was out of the country.
A C-130 was in Israel, but it wasn't going to get to Benghazi until brunch time the following day: and it too turned around when everyone was out of the country.