A senior U.S. official said Tuesday that 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.

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

However, Seiler said there has been no sign in the last two years that Pyongyang is willing to de-nuclearize, as North Korea's leadership seeks to develop its nuclear program despite sanctions and diplomatic isolation.

Seiler, speaking to the Center for Strategic and International Studies think tank, suggested that North Korea “may not have learned any lesson” from the Iran talks, and if it had, “we would perhaps 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, Seiler 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, which involve 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 halted the North’s nuclear development in exchange for U.S. food aid collapsed in 2012 after Pyongyang launched a long-range rocket and then conducted a nuclear test.

The U.S. and five other world powers reached a framework agreement earlier this month to prevent Iran from developing nuclear weapons in exchange for sanctions relief.

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

The Associated Press contributed to this report.