A series of Iranian officials vowed on Friday to expand Tehran's missile capabilities, a challenge to the United States which has threatened to impose new sanctions even as the vast bulk of its measures against Iran are due to be lifted under a nuclear deal."As long as the United States supports Israel we will expand our missile capabilities," the Revolutionary Guards' second-in-command, Brigadier General Hossein Salami, was quoted as saying by the Fars news agency."We don't have enough space to store our missiles. All our depots and underground facilities are full," he said in Friday Prayers in Tehran.Defense Minister Hossein Dehqan said Iran would boost its missile program and had never agreed to restrictions on it."Iran's missile capabilities have never been the subject of negotiations with the Americans and will never be," he was quoted as saying by Press TV, an Iranian state channel.The defiant comments are a challenge for the administration of US President Barack Obama as the United States and European Union plan to dismantle nearly all international sanctions against Iran under the breakthrough nuclear agreement reached in July. Iran has abided by the main terms of the nuclear deal, which require it to give up material that world powers feared could be used to make an atomic weapon and accept other restrictions on its nuclear program.But Tehran also test-fired a missile in October, which the United States says would be capable of carrying a nuclear payload and therefore violates a 2010 UN Security Council resolution which is still in place.Iran does not accept that the UN resolution bars it from testing missiles, as long as it has no nuclear weapons to place on them.