Former US ambassador to the UN Bill Richardson urged the United States on Saturday to engage in dialogue with North Korea, but only if Pyongyang refrains from further nuclear tests and missile launches. Richardson, a former New Mexico governor, and Google chairman Eric Schmidt visited North Korea last month in an unsuccessful bid to free Kenneth Bae, an American of Korean descent, who is being held in North Korea. Upon his return, Richardson has concluded that the lack of direct dialogue between the US and North Korea is not helping Washington achieve its goals.