There have been queries as to whether Christopher Nolan’s film Oppenheimer is a sequel or a prequel to his 2020 film Tenet due to their similar themes and the fact that Oppenheimer was referenced in Tenet.
Tenet follows a CIA agent (The Protagonist) as he manipulates the flow of time to prevent a global catastrophe.
Oppenheimer is a biographical film about the story of J. Robert Oppenheimer (also known as the “father of the atomic bomb”) and his role in the development of the atomic bomb.
So, are these two films connected? This article discusses the connection between the two films and whether Oppenheimer is a sequel or a prequel to Tenet.
Is 'Oppenheimer' Connected to 'Tenet'?

Oppenheimer is Christopher Nolan’s next film following Tenet, his 2020 science fiction movie. However, Oppenheimer is not a direct sequel to Tenet nor a prequel despite the reference made in the 2020 film.
It must be noted that Tenet is a work of fiction, while Oppenheimer is a biographical film (or biopic). Thus, it is unlikely that these two films are connected as their genres differ.
Furthermore, while these two films may share similar themes as they are both directed by Christopher Nolan, the latter usually approaches his projects as standalones (like Inception and Interstellar).
Additionally, Oppenheimer is based on the book American Prometheus: The Triumph and Tragedy of J. Robert Oppenheimer by Kai Bird and the late Martin J. Sherwin. So, Oppenheimer is not a sequel or prequel to Tenet.
Do You Need to Watch 'Tenet' to Understand 'Oppenheimer'?

Since the films are not directly connected, there's no need to watch Tenet first before watching Oppenheimer. However, you may want to consider watching Tenet in order to grasp Christopher Nolan’s style in his films.
And you may want to watch Tenet to see the scene where Oppenheimer is mentioned. For reference, here is the conversation that took place between The Protagonist and Priya Singh (an arms dealer) in Tenet:
The conversation revolves around a scientist in the future who built an algorithm that could destroy the past. She then took her own life so she couldn’t be forced to make another. Priya compares this future scientist to Oppenheimer.
You can watch the trailer for Oppenheimer below:
The film’s official summary, as provided by Universal Pictures:
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