As Sid Meier’s Civilization game taught me, privateering is explicitly not a declaration of war. It’s been used many times as a Cold War style tactic.

Now, Russia might declare ware and cite this as a reason, but it’s not. It’s more like state sponsored terrorism. Like how Iran isn’t actually declaring war on Israel with its Hezbollah sponsorship.

Similarly, the US wasn’t declaring war on the USSR when it armed Afghan rebels in the 80s.