The Serbs have been victimized, and they became victimizers. So too with Kosovo Albanians. The Arabs made the Israelis more aggressive by aggravating them, and the Israelis have had their own over-reactions. In international politics, keeping commitments, standing firm and a willingness to act are needed along with restraint. The accords created among the Allies at Paris in 1919 were also imperfect, but it was best to amend them through additional agreement, as the able German leader Gustav Stresemann did, rather than smash the accords as Hitler did.
Patience can be useful, but inaction can bring disaster.
In wars such as occurred in Bosnia late in the 20th century, where overwhelming military force is not being supplied by the international community, those defending themselves from aggression should be allowed to buy weapons. It is possible to fear an adversary too much. When possible, people should be allowed to be mistaken, for such allowances make freedom possible. Formulate law with sufficient detail and exercise law based on practicality. Pursing the law without practicality is a waste.