I believe this is a very complex argument that can’t be generalized. Each case has many sides of different stories.

From my opinion though, even in case of a war, God’s limits can’t be ignored and it’s important to be ready for peace as advised in the Quran.

However, as injustice overcame this world, peaceful measures couldn’t lead to a change or bring balance in favor of the weakest whose rights were intentionally neglected just to make the rich richer. So there is no alternative except the use of power (in a sense a war) because tyranny, abuses and injustice have gone too far, don’t you think?