SHIELD (MCU)

The Strategic Homeland Intervention, Enforcement, and Logistics Division is a U.S. government agency. Howard Stark was a founding member. Nick Fury is the current executive head of the S.H.I.E.L.D. Agents have included Phil Coulson, Natasha Romanoff, Jasper Sitwell, Clint Barton, and Maria Hill.

When Loki stole the Tesseract and escaped along with several enslaved S.H.I.E.L.D. personnel, Director Fury reactivated the Avengers Initiative to counter the threat. Agent Romanoff was sent to bring in Dr. Banner, Agent Coulson was sent to retrieve Tony Stark, and Fury himself approached Steve Rogers, all in the hope that together these individuals might combine their respective talents to help with the problem of Loki and the missing Tesseract.

S.H.I.E.L.D. assisted Rogers in his capture of Loki, and then provided a prison on the helicarrier once Loki had been apprehended. It transpired that Loki had intended to be captured however, a ruse to sow the seeds of discord throughout the ranks of the forces assembled against him. His mind-controlled agents later attacked the helicarrier to free him, heavily damaging it in the process. The attack became a bitter defeat for S.H.I.E.L.D, although Fury turned one of its defining losses into the motivational push that Stark and Rogers needed. In short order the remaining heroes set off in pursuit of Loki, and began referring to themselves as the Avengers.

During the Chitauri invasion in Manhattan, the World Security Council ordered the deployment of nuclear missile to the city in the hope of stopping the invasion. Two planes launched to carry out this directive, but Fury managed to prevent one from taking off, and then Iron Man intercepted missile from the other.

After the Avengers' victory and departure, S.H.I.E.L.D. continued its normal military activities.

(From the Marvel Wiki)