Former US Defense Secretary William J. Perry held a series of previously undisclosed meetings last year with a senior adviser to Iranian President Mahmoud Ahmadinejad to discuss Iran's nuclear program, The Washington Times quoted a source close to back-channel talks as saying on Friday. According to the report, the unnamed source called the talks that took place with Mojtaba Samareh Hashemi, Ahmadinejad's closest aide, "discussions, not negotiations," and explained that they were aimed at clarifying understanding of the two sides' positions. The Jerusalem Post could not independently confirm the report. It was not clear in the report whether Perry was acting at the behest of the Bush administration or others. Meanwhile in Washington, an official White House spokesman said that US President Barack Obama is not ruling out military strikes against Iran to stop its nuclear program. Asked if the military option was still on the table, White House spokesman Robert Gibbs said: "The president hasn't changed his viewpoint that he should preserve all his options." Gibbs told reporters that Obama believes "we must use all elements of our national power to protect our interests as it relates to Iran," he said. "That includes, as the president talked about in the (election) campaign, diplomacy, where possible, and that we have many issues to work through," he said. Ahmadinejad called Wednesday for "profound changes" in US foreign policy - including an end to support for Israel and an apology to the Islamic Republic for past misdeeds. Ahmadinejad also urged Washington to withdraw its troops stationed around the world. Two days earlier, Obama reached out to Muslims in in an interview with Al-Arabiya television and stressed the importance of engaging Iran. In his inaugural address, Obama addressed leaders of hostile nations by saying "we will extend a hand if you are willing to unclench your fist." In related news, Gibbs dismissed a report in Thursday's Guardian that the Obama administration was preparing a letter to Iran intended to warm relations and pave the way for direct talks between Washington and Teheran. "Neither the president nor the secretary of state has requested nor seen any such letter. That closes the book a little bit on that," he said. Gibbs added that it was "unclear exactly who" US officials would engage with in Iran. "There has to be some preparation and an understanding and respect by both sides," before any negotiations can take place, Gibbs said. State Department spokesman Robert Wood said "nobody from the administration has tasked anyone within the White House, the State Department to draft any letter to the Iranians," adding that "there are lots of ideas that are being bandied about." "Until that review is completed, we're not going to be able to outline how we're going to go forward with regard to engaging Iran," stressed Wood.