Get the M240Bs on the Embassy roof.
At least ten M61s or M134s on flexible mounts and 50,000-100,000 rounds of ammo per gun should be standard minimum issue for our embassies in dangerous countries.
When that distinctive buzzing noise appears and what looks like a Hollywood rapid fire laser starts scything through the attacking mobs, said mobs usually leave. Also useful against helicopters, aircraft and soft skinned vehicles.