Interesting links - should be noted someone yesterday was questioning why there were no other photos of the launch. In your second link there are several other images of the launch.
I've seen several variations of the image originally posted by skunkbayweather. I dug into that and could not find any images from a different perspective, but I did find several commenters who claimed they saw a flash in the sky around that time.
The skunkbayweather guy was pretty certain at first it wasn't aircraft, saying he gets shots of aircraft frequently and the missile image definitely wasn't aircraft. 2 days later, he changes his story, says the controversy is over because it was proven to be a helicopter with a light shining downward. um, no.
Canada - Victoria on the southern tip of Vancouver Island is just across the strait of San Juan de Fuca from Whidbey Island. Looking at the missile in the image from the weather cam if you assume it's beyond Whidbey Island (the strip of land underneath the missile) it could have been launched from the strait, not necessarily in U.S. waters.
I originally assumed it was one of ours, but not so sure now. Looking at the nations that are capable of submarine missile launch, who would be the best candidate? I am going to discount the DS-owned sub idea over crewing issues, as well as launch from land. Another possibility would be the Club-K missile in a shipping container but I think less likely as those are cruise missiles.