In Counter-Strike: Global Offensive, which operation introduced the Guardian co-op missions?

In Counter-Strike: Global Offensive, Operation Bloodhound introduced the Guardian co-op missions.

Operation Bloodhound launched in May 2015 and added missions, new weapon finishes, a new set of collectible content, and the Guardian cooperative mode. Guardian missions paired two players against waves of computer-controlled enemies, giving Global Offensive a structured cooperative activity alongside its competitive matches.

The operation also helped establish the mission-book format that became a recurring part of Global Offensive’s live-service updates. Players progressed through objectives and earned rewards rather than simply joining standard matchmaking.

Operation Breakout, Wildfire, and Hydra were separate operations. Their names are plausible alternatives because each also added missions or other substantial content, but Guardian is specifically linked to Bloodhound.