“Sending warships” is no more an act of war than embargoing oil supplies to Japan in 1940.
Firing artillershells onto a Fort Sumter.... that’s an act of war.
Your analogy would fit if the embargo included instructions to go fire cannon shells at the men on the ground of a major Japanese port city.
You do understand these ships had orders to use "force" to make them comply?
Firing artillershells onto a Fort Sumter.... that’s an act of war.
It's a response to an act of war already engaged upon.