[eldoradude]

Trident subs max missile launch depth is 150 feet, to as little as periscope depth. The images Q posted mean to me that it was sub launched. Here is the launch Q posted compared with a Russian anti-satellite missile launch:

Q - 20 second time lapse

Russian anti-satellite launch - unknown longer time lapse

Closeup of Q image -

Trident launch -

I think it was "D" for defense and a high altitude/LEO shot. What against...hmmmm.

[Axenolith]

The Q launch post is from a weather station skycam, it’s taking individual pics, AFAICT about every several minutes, so there’s no lapse in it, I think it was a serendipitous frame catch.