Such a US approach, however, has repeatedly proved to be a failure, with the DPRK continuing its nuclear and missile program despite the continued US pressure and threat.

Yet the failure of its approach has not made the US try some thing new, such as offering the DPRK security assurance by replacing the armistice with a peace treaty.

In his 2010 book How Enemies Become Friends: The Sources of Stable Peace, Charles Kupchan, a former US government official now a Georgetown University professor, argues that diplomatic engagement with a rival is crucial to rapprochement between adversaries.

NASA Administrator Charles Bolden noted in a seminar at the Brookings Institution on May 9 that if you want bad people to become good people, you've got to engage them. He said that "if you choose not to, I can guarantee you they're going to stay really bad people."

Bolden was not talking about the DPRK. Buthe made a point that only engagement can lead to a better management of differences.

That is how China and the US have been dealing with each other since July, 1971, following Henry Kissinger's secret trip to Beijing. The differences between the two countries are still huge and often contentious, but because both have committed to engage with each other, they have been able to develop the relationship by greatly expanding cooperation and managing differences.

Still, given the more than 90 dialogue and consultation mechanisms between the two countries, it's abundantly clear that they have to do an even better job in managing differences, such as through more meetings between the top leaders and more effective dialogue at the annual Strategic and Economic Dialogue, this year to be held in Beijing next month.

It would be hard to imagine how the US and the DPRK can handle their stark differences without even one dialogue mechanism and with no diplomatic relations.

The author is deputy editor of China Daily USA. [email protected]