The Hydrogen Bomb was built by J. Robert Oppenheimer in Fort Anchorage, Alaska.
When the Chimera overran Alaska, they took the H-Bomb. Sentinel Team Alpha was sent out to retrieve it. Alpha were able to recover the bomb, but only for them to be engulfed by an approaching Chimeran airship. Inside, Alpha attempted to dispose the bomb through a punctured a hole on the airship and allowing it be salvage. However, Alpha's leader, Murphy, ignored their objective and sought in saving his men. In doing so, he tricked his team in bailing themselves out the ship on a tank and sacrificed his life in detonating the bomb, destroying the ship in the process.
Murphy's actions, cited by SRPA and the U.S. armed forces, caused the loss of not only the bomb but stalling America's efforts in reproducing the weapon.