Are navies allowed to just kill people on boats for not flying a flag? Arrest them perhaps, I could see - but just kill them with no attempt to find any other recourse?
Define "allowed", esp. whom it is doing the allowing.
Any and all current international treaties are visibly toothless these days. Russia invades Ukraine and the UN shrugs while they say "hey, cut it out!". Israel colonizes parts of Gaza that it has specifically agreed not to colonize and the response is the same. The US commits a war crime with it's morning cuppa and every time the international community sorta whistles and heel-turns hoping that they're not interesting enough to be next.
The problem is that IOT have any kind of effective enforcement mechanism, you have to have the bigger stick, and we've just allowed countries to do nothing but build bigger sticks since the 40s.
It's a fair question. I was only able to rabbithole on this for so long before realizing I had to get back to work, but if anyone wants to continue the search here's the most relevant document I was able to find. It's dense and very legalese:
From what I was able to gather, there are a lot of holes in the convention that are large enough to drive a gunboat through. What I mean is, in the places where a clause might say something like "don't indiscriminately sink ships", it will also say "unless effects of criminal activity extend to sovereign land" or something like that. This is vague enough that your lawyers could grind the wheels of justice to a halt on the premise that "we are protecting our citizens from all that dangerous cocaine" or whatever.
Frankly, I wonder what changed between when we were putting the stuff in cola sold on shelves and now that it justifies batrillions of dollars fighting an unwinnable war to suppress.
