Ran Shen was a former S.H.I.E.L.D. agent who quickly climbed the organizational ladder and was neck and neck with Nick Fury as top spy. He was eventually selected as a deep cover spy to infiltrate China, causing very few people in S.H.I.E.L.D. to know of his existence.
In 1968, while Ran was on Mount Everest where he awakened the spirit of what appeared to be a Makluan called Nian. The dragon pierced Ran's chest with its claw giving him the power to fulfill his wishes. Shen showed up years later calling himself the Iron Nail, and presumably released former super-soldier Nuke into Eastern Europe, to attack individuals countries he perceives as enemies of America, also to have him engage the heroes Captain America and Falcon.
Later, with the assistance of Dr. Mindbubble, Shen hijacked the Gungnir Helicarrier with the hope to use it to start a conflict that would bring down S.H.I.E.L.D. and the United States permanently. In an effort to have the world see with their own eyes that S.H.I.E.L.D. cannot be trusted, they forced a mind controlled Captain America to pilot the helicarrier. However, Cap was able to break Mindbubble's hold and during the ensuing fight Mindbubble was knocked out of a broken window. This distraction gave Shen enough time to shift Gungnir into it's robot mode and have it attack the country of Nrosvekistan.