VIENNA – Iran's reluctance to discuss limits to its missile program in nuclear negotiations with world powers highlights the weapons' strategic importance for a country facing US-backed regional rivals boasting more modern arsenals. But while it is not at the heart of the talks over Iran's nuclear program, which center on the production of fissile material usable in atomic bombs, Tehran's longer-range missiles could become one of several stumbling blocks ahead. For the United States and its allies, they are a source of concern as they could potentially carry nuclear warheads. Washington wants the issue addressed in the quest for a comprehensive agreement in the decade-old nuclear dispute. Iran denies accusations that it is seeking the capability to make nuclear weapons. It insists that the missiles are part of its conventional armed forces and rules out including them on the agenda for the nuclear discussions.Iran has one of the biggest missile programs in the Middle East. “Iran will likely refuse to negotiate constraints on its missiles,” Michael Elleman, a senior fellow at the International Institute for Strategic Studies (IISS) think-tank, said. It was unclear whether the matter would come up during the latest round of negotiations between Iran and the six big powers – the United States, France, Germany, Britain, China and Russia – that got under way in Vienna on Tuesday. Washington and Tehran earlier this year set out contrasting positions on whether missiles should be raised at all during talks on a long-term solution to Iran's nuclear work that began in February and are supposed to yield an agreement by late July. Deputy Foreign Minister Abbas Araqchi, a senior member of Tehran's negotiating team, was in February quoted by state media as saying Iran's defense issues were not negotiable and it had no intention of discussing missile capabilities with the powers. However, a senior US official noted that a UN Security Council resolution adopted in 2010 banned all activity by Iran related to ballistic missiles capable of delivering nuclear weapons, and that “in some way, this will have to be addressed.” Former senior US State Department official Robert Einhorn, now at the Brookings think-tank, said there was “considerable logic” to tackling the ballistic missile issue in the context of what he called the nuclear weapons threat posed by Iran. “Given the inaccuracy of early-generation, long-range ballistic missiles, such missiles only have military utility if they carry munitions with a very wide radius of destruction, mainly nuclear weapons,” Einhorn said in a new report. Iran makes no secret of its missile development program, frequently announcing and televising the testing of new models with the apparent intent to show – for domestic and foreign audiences – its readiness to counter any enemy attacks. Its efforts to develop and field ballistic missiles have helped drive billions of dollars of US missile defense expenditure, and contributed to Israeli threats of possible pre-emptive military action against Iranian nuclear sites. Shortly before the start of the nuclear negotiations in February, Iran's military said it had successfully test-fired two new domestically made missiles, including a longer-range ballistic projectile with radar-evading capabilities. Defense expert Pieter Wezeman of the Stockholm International Peace Research Institute (SIPRI) said it was difficult to assess the missiles' performance due to a lack of reliable information. He cast doubt on whether Iran had managed to make them accurate enough to turn them into useful conventional weapons to attack military targets, but suggested they could still play an important strategic role. Elleman said Iran's Shahab-3 missile, or a modified version called Ghadr-1, would be the prime delivery vehicles for a nuclear warhead, while the longer-range Sajjil-2 program appeared frozen, perhaps because of technical problems. Those three missiles are believed to have ranges of up to 1,000 km, 1,600 km and 2,400 km respectively – putting Israel and potentially parts of Europe within reach – although their reach might be less if they were to carry nuclear warheads. — Reuters