This is more of a hypothesis, but if WWIII will happen within the next five years, here's how I think it will start:
>Kim Jong Un/the DPRK will respond to Trump's threat by threatening to attack Japan with nuclear weapons
>Japan basically becomes a hostage
>Trump will follow through with his "fire and fury" claim anyways and attack North Korea or attempt to overthrow the Kim dynasty
>The DPRK responds by attacking Japan with nuclear weapons
>somewhere between a minimum of 25% and a maximum of 75% of the world powers blame the situation on the US
>previously mentioned powers declare war on the US and partially side with the DPRK
>Hell breaks loose
>We're all fucked
Alternative scenario:
>DPRK responds to Trump's "fire and fury" threat by making a similar threat and hinting towards an attack on Japan
>Japam is a hostage
>Trump makes another threat
>The DPRK attacks Japan with nuclear weapons
>Scenario is the same as the last one otherwise
>Hell breaks loose
>We're all fucked
I also wouldn't be surprised if the DPRK attacked us around the same time as Japan. However, the DPRK will ensure that Japan will be relatively more devastated than us. The US will be under more pressure than ever before, and these attacks will take us by surprise because the DPRK has never followed through with their hundreds of empty threats.