UNITED NATIONS — Iran took its case against the United States to the United Nations on Wednesday and strongly condemned the top US military chief for saying military action remains a possibility if the country develops nuclear weapons.Iran's acting UN ambassador Eshagh Alehabib claimed in letters circulated to the secretary-general and presidents of the Security Council and General Assembly that Adm. Mike Mullen, chairman of the US Joint Chiefs of Staff, and other US officials and lawmakers "threatened" to use military action under the "totally false" pretense that Iran is developing nuclear weapons.RELATED:Iran asks IAEA to oppose sanctionsOdds of US strike on Iran could rise after Gates departureMullen said earlier this month that the US military has a plan to attack Iran although he thinks a military strike is probably a bad idea. Still, he said the risk of Iran developing a nuclear weapon is unacceptable and he reiterated that "the military option" remains on the table.Iran's supreme leader, meanwhile, told Iranian state TV that there will be no talks with the US under the shadow of threats.Ayatollah Ali Khamenei, who has the final say on all state matters in Iran, was apparently referring to recent calls by the US and other key powers for Iran to resume talks on its nuclear program following the UN Security Council's recent vote imposing a fourth set of tougher sanctions against the country for refusing to halt uranium enrichment.The US and some of its allies accuse Iran of using its civilian nuclear program as a cover to build nuclear weapons. Iran has denied the charges, saying its nuclear program is geared merely toward generating electricity, not bombs. Mullen said earlier this month that the US military has a plan to attack Iran although he thinks a military strike is probably a bad idea. Still, he said the risk of Iran developing a nuclear weapon is unacceptable and he reiterated that "the military option" remains on the table.Alehabib said the United States was using threatening language that violates international law and the UN Charter and goes against "global efforts to strengthen regional and international peace and security." He reiterated that Iran "would not hesitate to act in self-defense to respond to any attack."Khamenei said negotiations would be possible if the US stops making threats against Iran, and he set conditions for it."Talks under the shadow of threats and pressure is not dialogue. The Islamic Republic of Iran will never hold such talks," state TV quoted Khamenei as saying Wednesday. "We are for talks but not with the United States because America doesn't enter into negotiations sincerely."