In the developments of International Law, a recent dynamics developing is the idea of pe-emptivism.. What is pre-emptivism?
Again, as an angry state, United States is the main wager of the idea of pre-emptivism. This is a concept that basically proposes that in the name of self-sefence, states are allowed to conduct "peventive" actions. Meaning that upon intelligence information of a POSSIBLE threat, states allows themselves to make the first move in preventing that harm, by attacking the possible source of threat.
Can states do this? In International Law, it all depends on who's doing it haha.. If we want to analyze international regulation and customary (for comprehension on "customary law", refer to my previous post on the Si Omnes clause), pre-emptivism isn'nt actually regulated in detail. However, it can be inferred that it does not reflect the permissible circumstances of "self-defence". In international law, there are basically 3 pivoting references for regulating self-defence of a state;
1) United Nations Charter, article 51; a state could only wage aggression on another state in the name of self defenc upon imminent threat, and that it must undergo the consent of the United Nations Security Council.
2) Carolina Case; this basically happened in the end of 1890s, the turn of the century. At the time Canada was under the ruling of the British empire, and there was some rebels that fought against them. These rebels one day fled south to an island that's in-between Canada and the United States. The community in the bordering state of United States had incentive to help these rebels in terms of logistics, so they supplied the rebels with supplies, crossing the straits using a ship named SS Carolina. The Brits saw this as an imminent threat (because with logistics, the rebels can stay alive and therefore can keep threatening the peace of the empire), so they one day burned down this ship, killing 2 Americans, in the name of state self-defence. US and Britain went into trial, in which the court then decided to favor the US and stated that self-defence may only be viable under the circumstances that : the threats are real, it is imminent, with spread, and apparent. Up until now this case is still used as the precedence of self-defence cases, so it holds a universal value.
3) Nicaragua; you'd have to google this yourself because i don't really remember what happened here hahahaha..
As you can see, pre-emptivism isn't really reflected here; the idea of a preventive action does not show permisiibility here. Pre-emptive involves a lot of assuming, precognition, and prediction. It's complicated when India is gearing up their nuclear missiles but isn't actually threatening anyone, but on the other hand they do have political squabble with Pakistan over the bordering area of Kashmir. Yet India claims no threat but at the same time they test their missiles in an area very close to the borders of Pakistan. Can Pakistan see this as a threat? In the rules of law, no. In pre-emptivism? Plausible.
The rule of law internationally is a bit old-fashioned in this way. Because in the regulation it is stated that imminent threat means that the opposition is gearing up their troops, in an attack stance right outside their border. Urm, this is nice and all, but we've gone way past the ages of Colonial wars.
This is where International Law is tested. It again must evolve with the demands of International condition. This is where US plays benefit, where there is a loophole in the law, they take benefit.
God save us..