The Reach of ICC Jurisdiction Over Non-Signatory Nationals

A new International Criminal Court (ICC) was created on July 17, 1998 under the Rome Statute adopted by the United Nations Diplomatic Conference on Plenipotentiaries on the Establishment of an International Criminal Court. Under the Statute, the ICC will have jurisdiction over crimes of genocide, certain crimes against humanity, and certain war crimes, leaving the crime of aggression for further definition. Nonetheless, there are certain preconditions to the exercise of such jurisdictional competence, as noted especially in Articles 12-14 of the Statute. In general, the Court can exercise jurisdiction if a "situation" or case (1) is referred to the Prosecutor by a State Party to the treaty, (2) is referred to the Prosecutor by the U.N. Security Council, or (3) is under an investigation initiated by the Prosecutor "proprio motu." Article 12 adds that when a State Party has referred investigation, "the Court may exercise its jurisdiction if one or more of the following States are Parties to this Statute or have accepted the jurisdiction of the Court" by special declaration: "(a) The State on the territory of which the conduct in question occurred or, if the crime was committed on board a vessel or aircraft, the State of registration of that vessel or aircraft; [or] (b) The State of which the person accused of the crime is a national." The Executive Branch of the United States apparently considers that a U.S. national could not be tried before the ICC if the United States does not ratify the treaty.

Is this a proper interpretation of the treaty or of international law more generally?