What has caused this current conflict in Ukraine is the absence of real diplomacy by the West. Anyone could have foreseen the consequences of the relentless expansion of NATO to the east — that it would eventually cause Russia to react due to their security concerns. The Russians don’t want to see NATO-alliance missiles parked at their doorstep. Who would?
The obvious diplomatic solution to this situation would have been to do the following: guarantee that Ukraine would never be allowed to join NATO, guarantee from the Russians that they would respect the Ukrainian borders, and separate those Russian-majority sections of eastern Ukraine as separate republics.
But the West wasn’t willing to make the prudent compromise of keeping Ukraine out of NATO. So I ask you — who really is the aggressor here? NATO or Russia? Russia invaded, but NATO’s intransigence (and expansionism?) caused the problem.