He wanted to drag Romulans into war, which would mean thousands of them killed, including civilians.

He asks a former member of obsidian order, one he knows for sure that killed people in the past, he knows very well that is not a simple tailor, that’s why he asks him for help.

Sisko is involved in the process of convincing Romulans so that they get involved in the war.

A Romulan gets murdered and they go into war.

Shocked Sisko-pikachu face.