In the episode, alien time traveller the Doctor (Matt Smith) and his companion Clara Oswald (Jenna-Louise Coleman) land on a Soviet submarine in 1983 during the Cold War, where the Ice Warrior Grand Marshal Skaldak breaks loose and plots revenge against humanity.

Bringing back the monsters was Gatiss' idea, and he convinced executive producer Steven Moffat by coming up with new things to do with them.

Skaldak laments the loss of his daughter and his people; however, the Doctor tries to comfort him with the knowledge that the Ice Warriors still live, just not on Earth or Mars.

[1] Showrunner Steven Moffat had originally been hesitant to bring back the Ice Warriors, worrying that they were seen as "the default condition for what people thought of as rubbish Doctor Who monsters — things that moved very, very slowly and spoke in a way that meant you couldn't hear a word they said.

[4] Executive producer Caroline Skinner described the story as "Letting a huge Ice Warrior loose at the heart of a classic Hunt For Red October style submarine movie.

It was the first story in Matt Smith's era to use model work, with Mike Tucker and his team being specifically asked back to make the sub.

[3] Of the original design, Millennium FX's Neill Gorton said, "My problem with the old ones is they had Lego hands and weird, spindly arms but a bulky body and these strange saddlebag hips, almost feminine.

[15] In addition, "Cold War" received 1.65 million requests on the online BBC iPlayer during April, the fourth most-watched programme on the service for the month.

He praised the reinvention of the Ice Warrior and felt that the elements came together to form an episode that was "tense, tightly wound, claustrophobic but also full of heart.

"[20] Patrick Mulkern of Radio Times found an inconsistency with the TARDIS translation matrix, but overall was positive towards the acting, visual aspects, and story.

[7] Daily Telegraph reviewer Gavin Fuller gave the episode four out of five stars, describing it as "finely crafted" and "thrilling."

"[21] Digital Spy's Morgan Jeffery awarded the episode five out of five stars, saying that it was "fresh and exciting" but also had a "wonderfully old-school tone."

He wrote that it had "one of the best guest casts to have graced Doctor Who since the show returned in 2005" and also praised the reintroduction of the Ice Warriors and the production values.

Club gave "Cold War" a grade of A, highlighting the tense atmosphere, the "bold new direction" taken with the Ice Warriors, the guest performances, and Clara's importance.

On the other hand, Lewin noted that, as a base-under-siege story, it did not play with the narrative form or "go anywhere we couldn't have predicted," with the exception of the Ice Warrior breaking out of its suit.

Snow praised the reintroduction of the Ice Warriors and called Skaldak "the show's most memorable villain in a while, thanks to his stern, occasionally psychopathic approach to problem solving, and an environment that helped make the bulky, heavy creature design imposing rather than laughably naff."

Additionally, he disliked the revelation of Skaldak's true form, claiming it to look like "a not especially memorable CGI tortoise" and saying the BBC seems to have forgotten that "monsters are diminished when they're brought into the light", as well as worrying that it may have been "breaking a taboo for the show".