Blocking trade at the border does not necessarily require any military intervention other than turning trucks around.
As for the rest. Here is one of the core problems with the inspection regime. It never allowed full, complete, unfettered inspections.
Deep in the deal’s details is a procedure under which Iran would have to provide access to suspect sites, including at its military facilities, within 24 days. If Iran refused, it would face the possibility of U.N. sanctions being slapped back on it.
In the end, Britain, China, France, Germany, Russia and the United States agreed on language with Iran that requires more of Tehran than the existing global nonproliferation system while avoiding a direct mention of the sensitive military site issue.
This was a terrible deal from day one.