If US officials hope to make progress in their nuclear negotiations with North Korea, one task cannot be ignored: ending Pyongyang's highly enriched uranium programme. It would be a serious mistake, in the wake of the agreement reached in the six-party talks last month, to downplay the significance of the HEU programme.

Some US policymakers suggested that the US intelligence community is uncertain about the HEU programme, perhaps as a way of lowering the bar for North Korean compliance by allowing them to admit to only an experimental HEU programme. Such tactics, however, reduce Washington's negotiating leverage and we can expect North Korean negotiators to exploit it.