There’s a lot this issue, a whole lot. Moore introduces some characters and implies some back story, but he really is just bringing the world powers situation into focus. While there was talk of the Soviets before, this issue–especially the ending–finally establishes the ground situation. Moore had been keeping it a little bit of a secret.
This issue also features the introduction of the “Black Freighter” comic, alongside the nuclear fears, so it’s hard not to see the two tied. Even though Moore uses the comic-in-a-comic as transition occasionally, the connection’s clear.
Other big things, narratively speaking, include fully introducing Jon only to send him off into exile. Moore’s very subtle with his build-up to events; it isn’t just Jon’s TV interview being an aside in dialogue, it’s Dan realizing he’s out of sugar.
Watchmen is a gentle book, after all.
The issue’s amazing.