Imagine a hypothetical world in which everyone had decided to revoke the use of violence and refrain from war, preferring instead to live by universally accepted rules. Even in such a world there might sometimes be rogue elements who cheated, but in the rare cases of potentially violent mischief making, any side which felt itself put-upon would send a complaint to the world referees, who would call out the culprits, admonish them, and everything would go back to normal. Obviously, in such a world it would not be legitimate for anyone to retaliate with force, even when they felt attacked, since the world body would resolve the matter for them like an efficient nursery school teacher.
If, in exceedingly rare cases, some group insisted upon being unreasonable and aggressive, the world body could, at least conceivably, take action itself. This would be highly regrettable, but at least it would be clearly moral.
The odd thing is that there are people who sincerely believe this mumbo-jumbo, or at least pretend to. The Archbishop of Canterbury, for example, and others, too. For their benefit, here's a letter sent recently by a representative of the Israeli government.