Three more Senators have declared against President Obama’s Iran nuclear deal in recent days, and don’t be surprised if more follow after Wednesday’s bombshell from the Associated Press. The news service reports that Iran will be allowed to use its own inspectors at the secret Parchin nuclear site under its secret side agreement with the International Atomic Energy Agency (IAEA).

This is a new one in the history of arms control. Parchin is the military complex long suspected as the home of Iran’s nuclear-weapons and ballistic-missile...