(April 2012). A proof test is a form of stress test to demonstrate the fitness of a load-bearing structure, or rescue strop. An individual proof test may apply only to the unit tested, or to its design in general for mass-produced items. Such a structure is often subjected to loads above that expected in actual use, demonstrating safety and design margin.
The United States and North Korea do not have diplomatic relations. The Swedish Embassy in North Korea is the U.S. protecting power and provides limited consular services to U.S. citizens. The U.S. Special Representative for North Korea Policy is Ambassador Joseph Yun. The U.S. Special Envoy for North Korean Human Rights Issues is Vacant.
The involvement of U.S. government officials seems to be a common theme in the release of Americans. At least three Americans -- a student and two men who were held for perceived missionary activities -- were released from detention in North Korea in 2014. The AP reported that Director of National Intelligence James Clapper intervened and flew to Pyongyang to bring them home.