Yesterday, Assistant Secretary of State Christopher Hill said he wants North Korea fully to disclose its nuclear weapons program by the end of this month. “Everything we’ve asked them to do, they can certainly do,” he told reporters after a speech at Columbia University. “Everything we’ve asked them to do, they’ve already agreed to do.”

There is no question that the North Koreans failed to provide their promised declaration of nuclear activities by the end of last year. The issue is whether they have a legitimate excuse. Hill’s North Korean counterpart Kim Gye Gwan says the United States has failed to live up to its side of the bargain by not taking his country off the State Department’s list of state sponsors of terrorism and keeping American trading sanctions in place. Both of these actions were covered in an agreement reached last February as a part of the so-called six-party talks.

So who is at fault? The North Koreans have been making the point that Hill has been making side deals on the pace of normalization and that Washington has not honored the commitments it has made. Although Pyongyang’s diplomats are especially proficient at lying, Kim’s charges are not entirely unbelievable this time. After all, the current flap over the terrorism-sponsorship list and trade sanctions is reminiscent of the dispute over North Korean funds held in a Macau bank last year. During that imbroglio, Hill appeared to have made a secret commitment to Pyongyang to return those monies (which the United States eventually did in an especially humiliating climbdown).

Of course, we will never know what is going on until both the United States and North Korea open their archives. Yet there is one conclusion we can reach now: we always get into trouble when we engage in secret diplomacy with Kim Jong Il’s regime. There is no legitimate reason for the North Koreans to refuse to honor their promises. Yet we hand them excuse after excuse if we make secret concessions. If Hill can’t keep the diplomatic process on track without promising too much to Pyongyang, then the six-party talks are not sustainable and are not worth maintaining.