The second chapter of what I’m tempted to call Alex Garland’s “American Typewriter” series, “Warfare” plays like a concentrated B-side to last year’s sprawling “Civil War,” which leveraged the aforementioned font to lend an air of objective reportage to a fictional story about photojournalists covering the downfall of Western democracy. From a distance, that font might seem to be the only thing these two films share in common besides their director (and his signature ambivalence), as one is a provocatively speculative epic that ends with a ground assault on the White House, and the other is a violently grounded simulation that aspires to be the most realistic movie ever made about modern combat. Where “Civil War” was born from anxieties, “Warfare” is based on memories — specifically, the memories of a Ramadi surveillance mission that went sideways for a group of Navy SEALs during the Iraq War in 2006.

And yet,...