The talk doesn't currently amount to much more than grandstanding when North Korea has used the "declaration of war" rhetoric before, and is likely fully aware that firing the first shot would amount to a death sentence. The language of the tweet certainly doesn't suggest that an American first strike is imminent. However, this is the first time the North has used an internet post as a pretext for its bluster.

Also, the incident underscores the problems that can arise when political leaders post to social networks without any filters. Even an off-hand comment can spark a diplomatic row, and walking it back might not be as simple as deleting the tweet or issuing a quick apology.