In Tom Clancy's Splinter Cell 3D:

Sam Fisher is sent behind enemy lines in the Korean Peninsula to prevent WWIII, by investigating the responsible party that sunk the USS Clarence E Walsh, U.S.’s most advanced cruiser.

Through his investigation, Sam learns that the key parties who are planning to use the Masse Kernels and launch WWIII are war comrade Douglas Shetland, Displace International, and Admiral Otomo, the Third Echelon Information Self Defense Force (I-SDF) contact.
His goal is to infiltrate their lines and expose their deeds before they manage to launch a new and deadly worldwide conflict.