UNCLOS prevents U.S. from boarding ships without flag state approval, giving pass to rogue states

Similarly, counter-proliferation efforts at sea are hindered by UNCLOS Article 92, which provides that “ships sail under the flag of one state only and, save in exceptional cases expressly provided for in international treaties or in this Convention, shall be subject to its exclusive jurisdiction on the high seas.” That means that a warship must have the consent of the flag state or the master to board and search a foreign flag vessel encountered seaward of the territorial sea of another nation. The enforcement regime established in both UNSCRs 1718 (2006) and 1874 (2009), which ban most arms transfers to and from North Korea, is based on exclusive flag state jurisdiction. Although UNSCR 1874 contains an enhanced maritime cargo inspection regime, it is still dependent on flag state consent (Operative Paragraph 12). UNSCRs 1696 (2006), 1737 (2006), 1747 (2006) and 1803 (2008), which impose a similar ban on material related to Iran’s nuclear weapons program, are likewise based on flag state jurisdiction. Interdiction efforts on the high seas under other non-proliferation initiatives, like the 2005 Protocol to the Convention for the Suppression of Unlawful Acts against the Safety of  Maritime Navigation (SUA)¹⁹ adopted by the International Maritime Organization (IMO) and the Proliferation Security Initiative (PSI)²⁰ announced by President Bush in March 2003 to combat the growing threat of WMD proliferation, also suffer from the same weakness – they are based on flag state consent. It is highly unlikely that Iran or North Korea will give consent to a foreign warship to board one of its vessels at sea. In short, in could be argued that UNCLOS allows North Korea and Iran to transport WMD-related materials with impunity, hiding behind the concept of exclu- sive flag state jurisdiction on the high seas.