The United States Strategic Command is one of nine Unified Combatant Commands within the United States Department of Defense. Formed in 1992 with representation of the US Army and Navy, it is responsible for tackling cyber attacks; missile defense and combating weapons of mass destruction, such as Bio Organic Weapons.
In the Castle build for Resident Evil 4, Leon S. Kennedy was to cooperate with USSTRATCOM in an assault against Umbrella at the Spencer Castle. Albert Wesker's HCF forces were to unleash a new bioweapon in the area, wiping out all but Leon.
In reality, they are charged with space operations, information operations, missile defense, global command and control, intelligence, surveillance and reconnaissance (C4ISR), global strike and strategic deterrence (the United States nuclear arsenal), and combating weapons of mass destruction.