Without Remorse

The film adaptation of Tom Clancy's 1993 novel 'Without Remorse' had been in development since the 1990s when John McTiernan was attached to direct, Christine Roum writing the screenplay, and Brandon Tartikoff set to produce long before his death in 1997. In 1994, Keanu Reeves was offered $7 million for the role of John Clark but turned it down. In 1995, the film, which was set to be written and directed by John Milius and would star Laurence Fishburne and Gary Sinise, was two weeks away from shooting, before it was shut down, due to the financial collapse of Savoy Pictures. In 2012, Christopher McQuarrie signed on with Paramount Pictures to direct the film, with Tom Hardy in talks to play John Clark and Kevin Costner in talks to play his mentor, William Harper. In September 2018, it was announced that Michael B. Jordan would be playing John Clark in a two-part film series, which would be composed of 'Without Remorse' and 'Rainbow Six'. Director Stefano Sollima was announced in December 2018 and filming began in Berlin in October 2019.

When Kelly threatens Ritter with a gun in Murmansk one of the Russians tells about the plan where they receive money to transfer a guy to a US base in Finland. There are no US (or NATO or other foreign) bases in Finland.

During the end credits, John Kelly, now John Clark, meets with Ritter with a proposal to form a counter-terrorist unit called "Rainbow", setting up the events of the planned sequel, Rainbow Six.