US cannot go it alone on sanctioning Iran

US President Donald Trump has announced what was long anticipated: That he will not certify that Iran is complying with the July 2015 “Joint Comprehensive Plan of Action” (JCPOA) signed by the United States, China, Russia, France, Germany, the United Kingdom, and Iran.
Nor will he certify that the suspension of sanctions undertaken by the US as part of the agreement is justified and in the vital national interest of the US.