That's at best redundant. They became the enemy due to that particular military strike.

Not especially redundant and the "at best" has highly dubious connotations 'at best'. The "comprehensive military strike" is ambiguous without something that indicates whether it is "by us" or "by the other guys".

Even apart from that I wouldn't accept as remotely tenable the claim that Japan couldn't be described as an enemy just because active firefights were not in progress, in much the same way that the participants in a cold war cannot be enemies just because the war is cold. Would you really claim that prior to pearl harbor Japan during that war hadn't done anything that threatened American interests such that they couldn't be considered an enemy? Was America really naive enough not to realize that the previous actions of Japan and the positioning of their forces didn't make an enemy, even if it is one that America was until then able to leave to others to fight? Japan certainly didn't think so, or they wouldn't have bothered making a first strike while they were already busy.