Croatian National Guard (ZNG), later part of Croatian Defence Forces (HOS) were both paramilitary formations because in the time they've been formed only Constitutionally established and legal military force in Yugoslavia was Yugoslav People's Army (JNA). There has been much more (at least dozen) other small paramilitary Croatian units but these two were major. Croatian self-declared independence was then pushed against the Statute of Yugoslavia, thus illegal. But as Bryant said, unlike Russian minority in Ukraine Croats enjoyed strong political, financial and logistic support from the western powers who, in pursuit of their own strategic goals in the Balkans, decided to break international law, ignore Charter of the UN and Yugoslavian territorial integrity and to recognize Croatian secession, sending Yugoslavia into the nightmare of civil war.