Mr Martin would do his readers a service by relying on more than US State Dept. briefing notes and rehashed anti-Trump platitudes.

This escalation is only nominally about North Korea, it is really about the US vs. China and Russia who value NK as a buffer state from the US military in SK. The US was annoyed at China's militarization of newly created islands in the South China Sea, which is a potential threat to allies like the Philippines. Other than sailing ships nearby and flybys, nothing much was done under Obama. 

The projection of power under Obama was done by the CIA, with the debacle in Syria being the classic example. Under Trump, Defense is back in charge. 

The Trump Administration responded to their perception of Chinese and Russian aggression (though they call it self-interest) by expanding joint military activity with SK and Japan on North Korea's doorstep.

It was this expansion that lead to accelerated missile and nuclear development by NK, not the other way around.