[CamperBob2]

One impression that I got from the article, which I thought was helpful, is that Johns's work serves as a transition or bridge between the Abstract Expressionists like de Kooning and Rothko and the more modern figures like Andy Warhol.

The Wikipedia article on abstract expressionism actually comes right out and says as much. So I'd start there, if you want some contextual background.

[3chelon]

Yes, he's often described as an early Pop artist, but unlike the more famous Warhol & co., who used and embraced industrial processes, there's a definite "craftsy", home-made quality to Johns' work.

He used encaustic, which is a mixture of hot wax and oil paint, which lends the paintings a really unique texture. There's also often newsprint embedded in the paint, which adds another layer of texture.

Reproducing the American flag in this medium, and at scale, offers all sorts of questions. The red drips are maybe too symbolic, but the embedded newsprint gives a sense of history, and the whole handmade effect just adds to the ambiguity.

I once read some of his sketchbook notes, in which he'd written something along the lines of "try to hide what's going on from the viewer." So, he was being deliberately vague. And somehow it works, at least in his early works.