An interstellar war is a hypothetical space war between combatants from different planetary systems.[1] The concept provides a common plot device in science fiction, especially in the space opera subgenre. In contrast, the term intergalactic war refers to war between combatants from different galaxies, and interplanetary war refers to war between combatants from different planets of the same planetary system.[2]
But there are three huge problems with this plan, and combined, they could be tantamount to a declaration of interstellar war. It could be the first shot fired in a catastrophic interstellar war.
But the other two strategies are more common historically and would probably guide the course of an interplanetary war.