North Korea should learn from the emerging nuclear deal with Iran that Washington is willing to engage its adversaries if it has a “credible” partner to negotiate with, a senior U.S. official said Tuesday.

Sydney Seiler, U.S. envoy to long-stalled six-nation talks on North Korea’s nuclear weapons program, also cited Cuba and Myanmar as having “responded to our offer to reach out a hand to those who would unclench their fist.”