Former FBI agent warns Americans face an 'existential threat' from nuclear attack, cyberattacks and sabotage and must stockpile supplies

Chris Swecker, a 24-year FBI veteran and former assistant director of the Criminal Investigative Division, says cyberattacks could cripple America's financial system while sabotage plunges millions into darkness. He backs a public warning from former FBI Deputy Director Dan Bongino urging Americans to draw up emergency plans. Governments across the UK, Sweden, Germany and France have already told citizens to stockpile food and medicine.