Why do gas prices have to go up as a result of Russia's war on Ukraine?

I don’t mean what’s the rationale or justification. I understand about scarcity, supply and demand. There’s a lot of talk about what kind of pain people will be willing to bear at the gas pump. I don’t see anything about what the sellers (outside of Russia, presumably) might be willing to give up. Don’t they have to bear any pain?

What I want to know is, is there any discretion involved? Isn’t it just profiteering? Why do those prices have to rise? What would happen if sellers of oil and petroleum products didn’t raise their prices? Couldn’t they choose not to?

Or is it the buyers who actually drive the prices up?

Is it all about greed, or is it something else?

Call me naive. Go ahead, it would probably be true. But this isn’t a question about marketplace fluctuations. It’s about whether the rise in cost is somehow automatic or if the responsible people could hold prices steady if they wanted to.