He shared the news with all of his followers on Twitter yesterday, although these tweets were later deleted. Here is what he said.
Jasper Sitwell appeared as an agent of the espionage agency S.H.I.E.L.D., beginning in the feature "Nick Fury, Agent of S.H.I.E.L.D." in Marvel Comics' Strange Tales in 1966. Maximiliano Hernández first appeared as Agent Jasper Sitwell in Thor, and has appeared in Marvel's The Avengers and Marvel One-Shot: The Consultant and Marvel One-Shot: Item 47. He also provided the voice of this character in the animated series The Avengers: Earth's Mightiest Heroes. He did not, however, appear in Captain America: The First Avenger.
Captain America: The Winter Soldier comes to theaters April 4th, 2014 and stars Chris Evans, Scarlett Johansson, Samuel L. Jackson, Sebastian Stan, Anthony Mackie, Cobie Smulders, Robert Redford, Frank Grillo. The film is directed by Anthony Russo, Joe Russo.