Call of Duty: Warzone added a potentially powerful new killstreak with this morning’s huge update.
Bombardment is obtained from the freshly-unlocked Containment Monitor stations found across the map.
This new killstreak is listed in the Containment Monitor station menu under the Containment Protocol category, and requires a key to unlock. This lets you call in a missile barrage over areas affected by the zombie outbreak.
To get the key, you need to first activate the computer terminal in an outbreak area of the map. This starts the zombie event. Kill all the zombies and you get a yellow access card as a drop. You then use this to open the nearby yellow supply crate, which contains the Protocol Access card. This is used to unlock Bombardment from a Containment Monitor.