It is hardly a stirring moniker, but 2019 is going to be the year of “complementary measures.” As followers of North Korea know, “complementary measures” is the term Pyongyang has adopted to describe the quid-pro-quos that the U.S. must extend in order to see progress in the nuclear domain.

The current jockeying over the sequence of summits (North-South or U.S.-North Korea) and the structure of negotiations (working-level, high-level, leaders’ meetings) in the end comes back to the central substantive issue: what are the two sides willing to offer to get to a deal?