Sekou (J. Mallory McCree) is publicly identified as the driver of the Medina Medley van that exploded in New York.
Carrie (Claire Danes), having to attend to Sekou's family, leaves Quinn (Rupert Friend) to watch her daughter until babysitter Latisha arrives.
Quinn forcefully takes the reporter inside the house, harshly questions her, and throws her out down the front steps, inciting the mob further.
President-elect Keane (Elizabeth Marvel) is taken to a safe house by her Secret Service detail, led by Agent Thoms (James Mount).
An ESU squad attempts to enter Carrie's apartment, but Quinn disarms the first officer who gets in, forcing them to abort entry.
The episode received a rating of 100% with an average score of 8.23 out of 10 on the review aggregator Rotten Tomatoes, with the site's consensus stating "Tense, emotional, and reminiscent of earlier Homeland episodes, 'Casus Belli' returns its leading lady to the tense, high-stakes storytelling in which she truly thrives.".
While having reservations about how quickly the situation escalated with the Quinn standoff, Tallerico praised the performance of Rupert Friend and said the scenes there were "tense and really well-shot".