As this article says, Zelenskyy has said this on Twitter:
We are entirely justified in our responses against Russia’s oil industry, military production, and those directly responsible for committing war crimes against Ukraine and Ukrainians.
Do you agree with him?
I do mostly agree with him, but the answer is more difficult than a simple yes or no.
In this article from 2022, back when Russia was only attacking Ukraine, the question was posed the other way around. When is a target military and when is it civilian? And when is a civilian target a legitimate target?
A power station is (most often) civilian infrastructure, but can become a legitimate target to directly reduce military capabilities when the military draws power from that station. Military production facilities are also legitimate targets, as are oil facilities that provide fuel to the army.
But an oil terminal used for export is civilian infrastructure that does not directly benefit the army, but rather indirectly through a series of steps.
If it was Russia attacking an oil terminal in Ukraine (or US / Israel in Iran, or Iran in UAE or SA for that matter) I would say these attacks were not justified and were actually war crimes. And I would be backed by international law, because the civilian repercussions would have been greater than the military ones. A country at war will just reallocate their budget, so the military will still buy their weapons.
But since it is a country that is defending itself against an aggressor that has been targeting civilian areas for years now, these attacks on civilian infrastructure in Russia will actually help diminish civilian deaths (on the Ukrainian side).
So, with that being said, they are justified imo, but some targets moreso than others.