What can Ukraine bomb Russia under international law

What can Ukraine bomb Russia under international law?

Historian Timothy Snyder recently said in the STANDARD interview that he doesn’t understand why completely different rules should apply to the Russian-Ukrainian war than historically applied to all previous wars. Ukrainian economist and former trade minister Tymofiy Mylovanov recently criticized the apparent imbalance, according to which Russian planes, rockets and drones are constantly attacking cities, but Ukraine is prohibited by its Western partners from attacking positions on Russian territory with its modern weapons. As a result, there are situations near the border when Russia fires artillery from its country, and Ukraine cannot do anything about it. But what does international law actually say about this?