No doubt because I am a veteran editor, I am often asked which term is correct with regard to this war. So here is my advice:
- Russo-Ukraine war/War
- Russo-Ukrainian war/War
- Russia-Ukraine war/War
- Russian-Ukrainian war/War
None of the above options are grammatically incorrect, however, the reasoning behind their structure varies from term to term
Russo is a modifier that means/implies “related to Russia” – but it is not Russia – for that reason I do not/would not use it – this is not a war simply “related to Russia” – for that reason I also would not use Russo-Ukrainian War
The term I use is Russia-Ukraine War, which is a compound proper noun. It identifies both countries, and war should be uppercase – we don’t say World war II. For example, “the death toll in the Russia-Ukraine War has reached” – and not the weaker version “the death toll in the Russo-Ukraine war has reached”
Russian and Ukrainian are adjectives that modify war – unlike the choice above, where each word is a standalone noun – the key concept here is not just “war”; rather, it is a war between the proper noun nations of Russia and Ukraine – not a war between the modifiers/adjectives Russian and Ukrainian.
Irene/Irena/Irka.