Technically, Iran agreed to a nuclear non-proliferation treaty in, like, 1972, violated it which led to UN resolutions in the early 2000s, then agreed to a "Joi

Technically, Iran agreed to a nuclear non-proliferation treaty in, like, 1972, violated it which led to UN resolutions in the early 2000s, then agreed to a "Joint Comprehensive Plan of Action" (https://en.wikipedia.org/wiki/Joint_Comprehensive_Plan_of_Action https://en.wikipedia.org/wiki/Joint_Comprehensive_Plan_of_Ac...) in 2015, which led to a partial lifting of sanctions. (The US went crazy around this time and broke the agreement as well, but...) In 2019, Iran "suspended implementation" of "part" of the JCPoA. Treaties are generally treated as law by signatories. So, "illegal". Not that it really matters any; who's going to arrest a country?