Harvard’s Roderick MacFarquhar says the US needs China’s help in getting rid of North Korea’s dictator

... The Trump administration has some leverage in making a deal with Beijing, which also has compelling reasons to work with the United States on hastening the end of the North Korean regime.

First, a unilateral strike by the United States would be likely to drag China into the struggle anyway. Preparation and joint action would allow Beijing to protect its interests. With Mr. Kim out of the picture, Beijing would be free from the constant worry that the unpredictable Mr. Kim could set off a wider war in East Asia.

Second, Beijing could negotiate the removal from South Korea of the Terminal High Altitude Area Defense, a missile-defense system known as Thaad. Washington deployed it last year to protect South Korea against North Korean missiles, but Beijing fears it could also inhibit its own weapons systems.

Third, China could insist that United States military personnel leave a newly united Korean Peninsula, and that the united Korea be permanently neutral, like Austria after the withdrawal of Soviet and Western troops in 1955. American troops will not leave South Korea as long as Mr. Kim remains in power.

Ideally, both Washington and Beijing would pledge aid to assist Seoul in the mammoth task of rebuilding the threadbare North Korean economy.

It is easy enough to list the benefits to China and the United States of ending the Kim dynasty. Achieving a level of trust between the two rivals, capable of sustaining so momentous a joint operation, would be far more difficult. ...