In 1990, Liquid joined the British Special Air Service , becoming the youngest person in history to join its ranks, excelling at parachuting, rappelling, scuba diving, free climbing, and use of small arms and military vehicles. During the Gulf War in Iraq, he was assigned to an SAS unit to track down and destroy mobile Scud missiles. In truth, he infiltrated the Middle East as a sleeper agent for the British Secret Intelligence Service , but he was taken prisoner by the Iraqis and declared missing in action.  In 1994 , he was rescued by the . Government. 
Snake infiltrated the base alone, but quickly gained help in the form of Metal Gear REX developer Hal Emmerich and new FOXHOUND recruit Meryl Silverburgh , Campbell's niece. Metal Gear REX was a nuclear-armed bipedal walking tank developed in secret by the . Army and ArmsTech. Although he largely was in shape for the mission, he did end up exhausted after climbing the flight of stairs up to Tower A's roof, causing Campbell to briefly joke that Snake's mushing had him get out of shape. However, he ended up being tricked into activating Metal Gear due to misinformation supplied by Liquid (who had infiltrated Snake's support group by posing as Master Miller, having had him murdered three days prior). With the help of the two aforementioned, as well as his former comrade Gray Fox (now the Cyborg Ninja ), Snake succeeded in destroying REX and defeating the members of FOXHOUND, including Liquid. Prior to their final battle, Liquid taunted Snake with the knowledge that he had killed many of his brothers in the Next-Generation Special Forces , who like Snake, had been experimented on to replicate Big Boss’s genes.