Following that remarkable show summit in Panmunjom, we can expect that, in the near future, American and North Korean diplomats will begin talks which will determine exactly what kind of concessions the two sides will make in order to achieve the expected (and hoped for) deal. 

For the U.S., the UN Security Council sanctions, especially sectoral sanctions, are its major leverage. While the sanctions were introduced by the UN, they cannot be removed without the explicit approval of the U.S., which has veto power on the Security Council.