Intended by who? Are you saying the US government knew it meant war and had the foresight (and bandwidth) to arrange a coordinated propaganda campaign on the spot?

People just being naturally angry seems like a simpler and perfectly sufficient explanation. We humans are pretty much hardwired to respond like that: when we believe we've been wronged, a special brain mode kicks in that pushes us toward taking action (ideally a constructive one, but brain hardware doesn't enforce that).