[dmm]

Grrrr, I see what you're saying about having to break treaty with the TF in order to attack their ship. We're being limited again by SEIV's diplomatic model. You should be able to attack any ship you want -- enemy, neutral, allied, partner -- without being forced to change the diplomatic status. This happens all the time in real life, and countries don't necessarily declare war. Sometimes the neutral is embarassingly exposed as a gun runner and apologizes. Other times the agressor is shown to be in the wrong; sometimes he pays reparations, sometimes not. But it doesn't always lead to war.
Example: Chinese fighter pilot critically damages US surveillance/spy plane that was flying in what most countries consider international air space. Chinese fighter and pilot are lost. US plane lands without permission at Chinese air field, thus violating their territory. Chinese refuse to give plane back and hold US crew prisoner. Net result? Everyone yells. A few months later the US even lets China join WTO.
Regardless of your viewpoint on these events, they prove that SEIV's diplomatic model is too simplistic.