WASHINGTON — 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.”

But Seiler said there was no sign in two years that Pyongyang is willing to denuclearize, as its leadership seeks to develop its nuclear program despite sanctions and diplomatic isolation.

Seiler told the Center for Strategic and International Studies think tank that the North “may not have learned any lesson” from the Iran negotiations, and if it had, “we would perhaps have seen it earlier.”

He said that had although Pyongyang characterizes the U.S. as hostile and “out to crush” North Korea, the U.S. in fact seeks a different path and negotiations. Asked about any preconditions for negotiations, he said the North would need to halt its nuclear program and missile launches while any talks are underway.

“The entire international community is looking for this type of policy shift in Pyongyang, and that policy shift would be positively responded to,” Seiler said.

The six-nation talks, also involving China, Japan, Russia and South Korea, were last held in 2008. The last official negotiations between Washington and Pyongyang were three years ago. An agreement that would have granted U.S. food aid in exchange for a nuclear freeze by North Korea collapsed in the spring of 2012 after the North launched a long-range rocket and months later conducted a nuclear test.

With Iran, the U.S. and five other world powers this month reached framework agreement to prevent Tehran from developing nuclear weapons in exchange for sanctions relief.

Three years ago, the Obama administration normalized diplomatic relations with former pariah state Myanmar. It has also begun high-level contact with Cuba in attempt to normalize ties with Havana after a half-century of estrangement.