All US Presidents from Reagan, to Bush 1, Clinton, Bush 2, Obama and Trump have failed to reverse the North Korean Nuclear program. Presidents from Eisenhower to Carter failed to prioritize and solve the North Korean rogue state issue.

China has long feared a refugee crisis flooding its borders if North Korea's leadership collapses. South Korea does not want to pay the price of a second Korean war.

China does not want a unified Korea and China and Russia have seen some utility for North Korea in its current state.

Sanctions have not worked because China has not enforced them on their end. China accounts for more than 90 percent of North Korea's trade, it would be ideal for them to cut back that trade significantly. The problem is that Chinese officials have long feared that doing so would not only cause a collapse, but it would turn Pyongyang against them.

The USA would have to offer China a huge deal to entice China to not only give up North Korea but to prevent or make up for all of the big downsides.