With all kinds of fake bogus "Islamic" Jihadi terrorist groups appearing in these days, that give a tremendous bad name to the real Islam, the world is in dire need to know what Islam says about warfare!!!
First it has to be realized that many of those groups are created and sponsored by the enemies of Islam, and creating Islamophobia! Even if one doesn't believe this, then still one should not judge and discuss unless having researched the subject of Islamic Warfare from Islamic sources. (Not from lying hate-sites).
Prophet Muhammad (PBUH), issued strict orders to the commanders of Muslim armies not to kill women, children, old and infirm men, not to cut down fruit-bearing trees and crops, nor to slaughter animals whose flesh was not eaten.