Electronic Arts posted in its Medal of Honor: Warfighter FAQ that the single player campaign for the military shooter would be between 5 and 15 hours long.
According to the FAQ's answer to the question, "Approximately how long is the single player campaign?", it answered, "The single-player campaign will consist of roughly 10 hours of action ripped straight from the headlines and missions of Tier 1 Operators from around the globe with 12 full-missions each taking place in a different "hotspot" of the world."
The FAQ question and answer was subsequently pulled by Electronic Arts, but still remains in Google cache.