President Donald Trump's official White House portrait. Photo: White House

President Donald Trump on Monday issued an executive order directing the Defense Department to restrict waivers sought by defense contractors when sourcing critical materials from adversary nations, specifically China, Iran, North Korea and Russia. The July 20 directive would still allow the Secretary of Defense and the military secretaries to issue waivers if a defense prime or subcontractor provides a plan for mitigating their reliance on covered materials from adversary nations, or if any of the secretaries get permission from…