Iranian Potential Countermeasures to US Acts : in Conformity with International Law?

When the Trump administration withdrew from the nuclear deal in May 2018, Iran not only remained in the legal framework, it took its grievance with the US as a legal dispute to the ICJ, specifically in relation to the breach of the nuclear deal and the reimposition of sanctions, as well as the freezing of Iranian assets in US jurisdiction. The killing of Qassim Soleimani has made things worse between the two countries putting the region in a turmoil. The possible outcome of this can be dangerous as Iran promised to take intelligent and proportionate countermeasures. The fear of escalation of the tension is growing day by day. Iran can close the Strait of Hormuz in which exist a legal vortex as neither the US nor Iran are signatories of the 1982 United Nations Conventions on the Law of the Sea (UNCLOS). It threatened also to enrich uranium declaring that it had the capacity to enrich uranium to 20% if needed.