My guess is nuclear test.
Airport circle to secure the transport of the device to the ground adjacent to the test site.
Trapezoid is the test site, wider on the side that is less controllable (border-facing).
Disconnected because two separate teams executed in parallel without informed oversight.
While Mexican side has no restrictions - that would be supremely dumb even for a primary school level of thinking. Tons of civilians dead with clear reason who caused it, completely preventable.
Fantasy often likes extreme options but most probably saner reason like expected strike on cartels and their retaliation is whats happening.
... I don't think they're detonating a nuclear weapon in a National Monument 50 miles from a large US city...
There are plenty of better places for them to do this.