Fort Strong

This military installation now has supermutants inhabiting it. The area around the main building is littered with radioactive drums but don't have much notable loot so you don't have any reason to linger near them either. You may also encounter a Legendary Super Mutant in the area outside the building.

Before reaching the main fort proper, you'll find a Power Armor with Fusion Core in the guard house.

Fort Strong Armory

From the lobby, unlock the Novice door to the right and kill all supermutants. There's another Novice locked room to the right as well. Loot the Fort Strong Key from the desk, the U.S. Covert Operations Manual on top of the desk, and the mini-nuke in the corner. There are also more ammo in the steamer trunk in the same room. In another corner of the room, you'll find a Safe which you can unlock using the key from the desk. Loot its contents.

The kitchen has Nuka-Cola, Cherry, and two Quantums in the Nuka-Cola machine. There are two more mini-nukes found in the shelf next to the doorway leading to the room with crates.

During the quest "Show No Mercy", the rubble blocking the elevator to the SE will be cleared and you'll be able to reach the lower level of the fort. You can find two mini-nukes on the shelf beside the empty mini-nuke shells in an open shipping crate.