The unnecessary and overwhelming exaggeration by experts who ought to know better is quite alarming.  For example the comment that the US is "entering its greatest isolationist phase since the end of the First World War. "  Seriously.  We do recall that the US stood by and watched while Germany attack Poland, Russia, France, many others, and even the UK without doing anything in 1938-39.  Does the author really want to stand by his statement?  

His hyperbole just undermines the rest of his argument, which is otherwise sound.  If we really do believe the US has become an unreliable ally - and I don't believe that- then we need to spend a hell of a lot more money on defense.  Like 3x-4x.  Even if we think the US will remain our ally, we should still pull our weight and spend 50 percent more.