Secretary of State Mike Pompeo should summon Russian Ambassador Anatoly Antonov and issue him a warning: unless Paul Whelan is immediately provided with better treatment, and regular consular access to U.S. diplomats, President Trump will cancel his planned meeting with Vladimir Putin at next month’s G-20 summit in Japan.

Currently detained in Moscow, Whelan is a former U.S. Marine who has been held for five months without any semblance of due process. And as the BBC’s Moscow correspondent recorded, Whelan says Russia’s FSB domestic security service is treating him terribly.