“Act of war against neutral countries in Asia?”
We had a secret arrangement with Cambodia that “allowed” us to bomb the trail in their country. We were attacking NVA “trespassers”. The same may have been true in Thailand.
Bombing of targets inside a NATO country by Russia would be quite a bit different IMHO. Not to say that Russia might not have a reasonable argument/fear of those arms - but it sure would escalate things.
Even an attack on a European ship in open waters would be a huge deal.
It would be different in the fact that Cambodia and Thailand were neutral and were unable to stop weapons being trafficked from a belligerent, North Vietnam, through their countries. Bombing NATO weapons being transferred through NATO countries is much more legitimate than bombing neutral countries trying to stay neutral. Putin is much more justified than Johnson or Nixon. Ever consider that we were half a world away trying to stop the first domino from falling, Russia is on its border, 300 miles from Moscow, is desperately trying to keep the LAST domino from falling. We would be less guilty had the US shown the restraint Russia has so far when we were brutally bullying Vietnam, Iraq and Afghanistan for reasons much less justified than Putin’s.