Oil speculation or terrorism?

The New York Times reports:

A Japanese oil tanker was damaged Monday when it was attacked by a small boat in Middle Eastern waters off the coast of Yemen, the tanker’s owner said. Word of the attack helped to drive world oil prices to a new record.

Considering that nobody was injured, this was a Japanese vessel, and the Japanese aren't allowed to go on a war footing since they lost WWII, I'm going to go out on a limb now and admit I suspect this wasn't meant to do anything other than send oil prices higher.