North Korea appears to have missed an important lesson from the breakthrough deal on Iran's nuclear program: that the United States is committed to negotiations even with long-time foes, the U.S. envoy for nuclear talks with Pyongyang said Tuesday.

Sydney Seiler, special envoy for the six-party talks on the North's nuclear program, made the remark during a seminar in Washington, stressing that the Iran deal clearly demonstrated "the flexibility, the creativity, the commitment to negotiations" that the U.S. maintains.

"The progress in our nuclear talks with Iran clearly demonstrates our willingness to engage countries with whom the United States had long-standing differences and there should be no doubt we continue to remain committed to negotiations, and a negotiated resolution of the DPRK nuclear issue," the enovy said during the seminar at the Center for Strategic and International Studies.

"It is the DPRK, however, that has not yet decided to embark on this path. It has repeatedly rejected offers for dialogue. It has repeatedly and openly violated commitments ... to abandon its nuclear program. It continues to ignore international obligations," he said.

Seiler also said that not only the Iranian nuclear deal, but also the breakthroughs in U.S. relations with Cuba and Myanmar demonstrated the "willingness, the flexibility, the creativity that the U.S. can show when it has a credible dialogue partner."

"They (the North Koreans) may not have learned any lesson (from the Iran nuclear deal). If they had learned any lesson, then we would have perhaps seen it earlier," he said.

The six-party talks aimed at resolving the North Korean standoff have been stalled since late 2008. North Korea demands the unconditional resumption of negotiations, while the U.S. says that Pyongyang must first take concrete steps demonstrating its denuclearization commitments.

As the six-party talks have been idled, the North has bolstered its nuclear capabilities and stockpile, conducting its second and third nuclear tests, in 2009 and 2013. Some experts now warn that the communist nation's nuclear arsenal could expand to 100 bombs by 2020.

Seiler said the U.S. is "not afraid" and "not ideologically opposed" to talking to the North, but he stressed that negotiations must focus on denuclearization and the communist regime should also halt its nuclear activity and refrain from nuclear and missile tests before talks resume.

"We seek negotiations ... And indeed the entire international community is looking for this type of policy shift in Pyongyang and that policy shift would be positively responded to," he said. (Yonhap)