U.S. Defense Secretary Robert Gates says there needs to be concrete actions by North Korea to demonstrate that it’s truly serious about negotiation and engagement.

Gates made the remark during a news conference after a meeting with Chinese President Hu Jintao on Tuesday in Beijing.

Gates called North Korea a direct threat to the U.S., while pointing out that the reclusive state will be capable of striking the continental U.S. in five years with intercontinental ballistic missiles potentially capable of carrying nuclear warheads.

Gates then said North Korea must pursue concrete measures before the U.S. will agree to return to the six-party talks and called on Pyongyang to institute a moratorium on missile and nuclear testing.

Gates said that during his meeting with Hu, they also discussed key bilateral military issues amid a friendly atmosphere.