How long has the Winter Soldier been active?

Question

In the movie, we see flashbacks to the creation of the Winter Soldier, at the end of which they say "put him on ice", and we see him frozen in some sort of suspended animation. This presumably explains how he was created in the WWII era but doesn't look like a 70-year-old today.

However, Black Widow says the Winter Soldier is responsible for numerous assassinations in the last 50 years, seeming to indicate he was active during this time and not frozen.

So was the Winter soldier active for the last 50 years, or was he only recently revived? If the former, why is he so young? If the latter, what should we make of Black Widow's comment?

Answer 1

Short Answer: About 50 years.

Bucky Barnes, AKA the Winter Soldier, is held in stasis between his missions due to the instability in the mind-wiping and mind control technology used to keep him from remembering his past.

Marvel Comics Historical Information

• Soon after the drone’s explosion, Russian General Vasily Karpov found a one-armed, frozen Bucky. The boy was revived in Moscow but suffered greatly from amnesia as a result of the explosion. General Karpov took advantage of Bucky’s amnesia, reprogramming him to become a Soviet assassin called the “Winter Soldier.” Karpov replaced his missing arm with a metal bionic arm that’s constantly updated with the newest technology.

• Over the years, the Winter Soldier has ruthlessly committed political assassinations that greatly impacted the Cold War. According to Marvel’s profile on the Winter Soldier, he’s an Olympic-level athlete and talented acrobat. He’s also highly skilled at hand-to-hand combat, whether he’s armed or not, and is an incredible marksman. In addition to these physical talents and abilities, he’s also proficient in Russian and German.

• Karpov’s exploitation of Bucky’s amnesia was not without its complications. The amnesia makes him mentally unstable, so he is kept in a cryogenic stasis in between missions (which also explains why he looks like he hasn’t aged much since the 1940′s).

In the Marvel Cinematic Universe

• Bucky survived the icy plummet off of the speeding HYDRA train. How? Well, when Rogers found him during that first extraction mission, Bucky was strapped to a table in some sort of lab. Considering that the Red Skull was hell-bent on reproducing Dr. Erskine’s formula, it’s easy to infer that the experiments that Bucky was subjected to somehow helped him survive the fall from the train.

• HYDRA operatives found Bucky frozen in the river and revived him before bringing him back to one of their bases. As shown in one of the Winter Soldier’s memories in Captain America: The Winter Soldier, HYDRA scientists and Arnim Zola (presumably after Zola was granted clemency by SHIELD) amputated what was left of Bucky’s left arm and attached a bionic one in its place.

• HYDRA completely brainwashed and reprogrammed Bucky to make him into the Winter Soldier, a highly-trained and dangerous assassin who would work on their behalf. As in the comics, the Winter Soldier was cryogenically frozen in between missions, which accounts for his youthful appearance.