[mattkrause]

Speech can certainly be an action.

"I'm running now" doesn't make you jog if you're sitting down, but it certainly kicks off a campaign if you were considering elected office.

JL Austin called these sort of statements "performative utterances" and there's a lot of linguistic debate about them. Nevertheless, "I declare war", uttered by someone with the power to do so, is pretty unambiguously an example of one.