(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.
On the other is the US, with a president using Twitter to threaten North Korea and whose country just deployed the Mother of All Bombs. And China is in the middle, fearful of feeling the destructive consequences of the others' warring. All China really can do is sound the alarm and hope it is heeded.