USA and North Korea
I'm more than a bit scared of the fact that Trump is going to be talking face to face with North Korea's leader. Neither of them project the most stable personality to the world, and there has been a distinct lack of tact displayed by Trump. Previous presidents had well informed and articulate people in their administrations, and still didn't manage to get a accord with the North Koreans, how on earth can Trump with his tendency to resort to playground taunts and nicknames?
Not to mention the fact that he has just fired Tillerson, who had been establishing connections over the course of the Trump presidency. How long will it take for the replacement to feel comfortable in the role?