At E3 2011 we got our hands on Call of Duty: Modern Warfare 3's new Spec Ops mode, "Survival". Survival mode features endless waves of enemies that you have to take out using a variety of weapons which unlock as your progress. Kevin Kelly got to test out Survival mode, here's a snippet from his preview:
"Finding a good corner to defend is one of the keys to surviving in Survival mode, but when the dogs and Juggernauts start rolling in, you'll need to go mobile. Luckily, there's an Air Support armory you can unlock, which offers tactical items like an Attack Helicopter, or even a Delta Squad drop-in, where four AI soldiers join and fight alongside you. They can (and will) die, but they're fairly intelligent, will follow you, and are very handy in a firefight. Especially once the suicide bombers start coming in. If they get near you, they'll explode, and if you down them, they'll blink red and then ... explode. But if you think that's bad, just wait until the dogs strapped with C-4 start coming after you. Someone in the Call of Duty world sure hates dogs."
To check out the other weapons you get while you try to survive the onslaught of enemies, be sure to read Kevin's full Call of Duty: Modern Warfare 3 Spec Ops preview.