Iran's UN envoy says the most important thing world powers can do at upcoming talks in Istanbul is to recognize that his country is a powerful player with ‘nuclear capability’ that is ready to cooperate on major issues, including non-proliferation. Ambassador Mohammad Khazaee warned on Tuesday that Iran will never respond to sanctions, threats or political and economic pressure. He said the Islamic Republic is not worried about international sanctions.Khazaee told journalists in New York that Iran wants talks with the five permanent members of the U.N. Security Council and Germany set for later this week to focus more broadly than just on its nuclear program. He said Iran hopes to make clear it is prepared to cooperate on issues in different areas like Afghanistan and Iraq, fighting terrorism and drug trafficking and especially, disarmament and nonproliferation.The Iranian envoy also accused US President Barack Obama of failing to live up to his promise of engaging with the Islamic Republic. Obama administration officials say it is Iran that has rebuffed Washington's offers of engagement by refusing to take steps to prove that its nuclear ambitions are peaceful.Khazaee reiterated that Iran's right to a civilian nuclear program is not negotiable. Iran denies Western suspicions that it is building an advanced nuclear weapon.