Critics continue to question whether North Korea can be trusted, as working groups meet this week in Beijing to carry out the first phase of a step-by-step agreement to resolve the crisis over the communist country’s nuclear weapons program.

The agreement, still in its early stages, is more about performance than trust. If North Korea and the United States – and the other four nations that are parties to the agreement – perform as promised at each stage, the diplomatic process can keep going forward. If either side cheats or stalls, the entire process could break down.

Suspicions center on whether North Korea is secretly making uranium-based nuclear weapons in addition to the plutonium-based devices that it acknowledges and even boasts about. The Bush administration used the uranium accusation in 2002 as justification for breaking off from a 1994 nuclear freeze agreement that the Clinton administration reached with Pyongyang.

Now, after four years of off-and-on diplomacy punctuated with charges and countercharges of bad faith, serious talks are back on track. Secretary of State Condoleezza Rice has been guiding the negotiations after quietly getting rid of some of the most hawkish opponents of any deal. And a top U.S. intelligence official on North Korea has reduced the “confidence level” of the belief that the suspected uranium refinement has gone forward on a scale to make bombs.

The initial phase of the six-nation Feb. 13 agreement for eventual denuclearization of the Korean Peninsula seems to be going smoothly so far. Mohamed ElBaradei, the director of the United Nation’s watchdog, the International Atomic Energy Agency, visited North Korea this week. He hoped to obtain a timetable and terms for inspectors to verify a shutdown of the country’s plutonium plant at Yongbyon by mid-April as envisaged for the first phase of the agreement. In return, North Korea is to get energy aid and security assurances.

Yet to come is North Korea’s promised disclosure of a full list of all its nuclear programs and their eventual abandonment. A big question for the future is what that list will say about the suspected uranium-enrichment program. The United States said in 2002 that North Korea had admitted existence of the program. Its officials insist that they merely asserted their right to refine uranium. The main U.S. evidence for the charge is the known transfer of 20 high-tech centrifuges from Pakistan to North Korea. Many more would be necessary for effective production.

The lurking uranium issue causes critics to ask whether Pyongyang can be trusted. Probably it can’t, no more than Pyongyang can be expected to trust the United States. That’s why performance – doing the things required by the Feb. 13 agreement – is more important than trust.