Look, she was the one suggesting wars could be solved with thinking, as if the people waging them haven't put any thought into it. They just have different priorities. Sephiroth would cite greed, mainly.

"...is that not a retaliation?" They don't have nuclear bombs on his Planet, but he's read enough to have some context. Surely if someone drops a bomb on you, it's either a declaration of war or the war is already in progress.