India, March 27 -- The US-Israel strikes on Iran which Israel described as a response to an "existential threat", raise a troubling question: Can States use force based on what might happen in the future? International law allows the use of force only in limited circumstances, such as self-defence. The United Nations (UN) Charter permits self-defence under Article 51 only "if an armed attack occurs," a threshold long treated as central to the legality of force. It does not authorise force in response to threat in general, nor does it permit military action based on vague or future fears. The International Court of Justice (ICJ) has repeatedly held that only the gravest forms of force qualify as an "armed attack". Not every unlawful act cr...