The US is gearing up for a demonstration of it's new Lockheed Martin F-35 Lightning II jets. North Korea is providing the perfect opportunity. When all is done, be ready to count the headlines in which the F-35s appear.
There are a variety of factors in the North Korean conflict. As you count them, don't exclude the need for the US to show force in the region. Just two examples include Putin's manners in Crimea—where Russian soldiers flew a flag over a building they had taken before a proper referendum became final—along with China not playing by UN rules with its man-made islands, yet remaining a UN member. There are other situations in the region.
Suffice it to say that North Korea is a perfect opportunity for the US to beat its chest and clear its throat for all to hear. Were there no such need, the US military presence might be a lot more low-key in the process of North Korea's government being on the way out anyway. Always remember that Washington occasionally thinks like Hollywood—in the White House as in the Capital Building and at the Pentagon. America loves theatrics and, knowingly or otherwise, nearly all Pacific nations played their roles as the foil.
Once Korea becomes one nation, tryouts for the next performance will likely soon follow.