This arose around some comments on "Is it true that the US president can execute anyone without a trial?"
Under the traditional rules of war you are not allowed to simply kill all of your opponents but are supposed to take prisoners of war when possible
No. Legally Russian military has no right to kill or murder anyone. If a soldier receives an order to "kill" the enemy he legally should refuse to follow it. Orders only can be of the form like "push the enemy from the place A", "capture place B", "strike place C (say, command centre)". There can be order to strike enemy infantry, but not to kill enemy infantry - there is a difference. Everybody always has right to surrender. I know that Russian secret services recently assassinated some people abroad, such as terrorist Yandarbiev but my conviction it is illegal and a borrowing of US methods. Comments might be deleted soon
Is there any international law, or convention (including Geneva) which compels any country participating in a war to take prisoners when a person fighting on the opposing side DOES NOT wish to surrender? (as opposed to simply killing everyone they can on opposing side as long as they don't try to surrender explicitly).
Is there something in sovereign law of major countries (I'm specifically interested in USA, USSR-or-RussianFederation, and France) which compels their military to do so, independently of international law (e.g. a law which would make an order to kill all opposing fighters - instead of offering to surrender, and/or trying to capture as POW - be an illegal order)?