Iranian Shiite Muslims pray in Tehran early on July 7, 2015 in commemoration of the death of the seventh century Imam Ali bin Abi Taleb and in preparation for Laylat al-Qadr -- a high point during Ramadan when the Koran holy book was revealed to Prophet Mohammed. Imam Ali, the first male convert to Islam, is the fourth caliph to succeed Prophet Mohammed, his cousin and father-in-law.

A PROPOSAL to allow Iran's military have powerful new conventional weapons in a nuclear deal is proving a stumbling block with Washington.

The concession, suggested by Russia, would make it extremely difficult for President Obama to sell an agreement to an already sceptical Congress.

Russia is pressing to end a United Nations arms embargo on Iran at a time when the Islamic Republic is already poised to add potent offensive weapons to its arsenal, with or without a deal. Analysts, citing satellite imagery, say the Iranian military is on the cusp of producing armour-busting bombs, a capability few nations can claim.

"Part of the reason the administration is going to care about this a great deal is that Congress will use it," Gary Sick, a former National Security Council official under three US presidents, said of the Russian bid. "Opponents of the deal will say Iran has a free hand to develop anything it wants."

Negotiators of six world powers and Iran are in the 12th day of their latest bid to craft a final agreement, having given themselves an extension beyond Tuesday's deadline. Russian foreign minister Sergei Lavrov said ending the UN weapons ban was the only major sticking point on the sanctions relief Iran demands as the price of a nuclear pact.

"It is essential to reach an agreement on lifting the arms embargo as soon as possible," he told reporters at talks in Vienna. Giving Iran access to weapons to combat terrorism "is a very important task", he said.

Russia also plans to start supplying S-300 anti-aircraft defence systems to Iran this year over objections from the US and Israeli, ending a self-imposed ban from 2010.

In Washington, US Defence Secretary Ashton Carter staked out a tough stand when asked about ending the UN ban on selling or buying seven categories of weapons, including tanks, fighter aircraft and missiles.

"We have serious concerns with Iranian malign activities outside of the nuclear issue," he said in Senate testimony.

A US administration official suggested greater flexibility, saying that the nature and duration of a continued arms embargo were subject to negotiation.

Russia is poised to reap $7 billion (€6.3bn) from arms sales to Iran over the next decade in the event of a nuclear deal, according to Ruslan Pukhov, head of the Moscow-based Centre of Analysis of Strategies and Technologies, which advises the defence ministry. The Islamic Republic needs a "huge upgrade" of its fighter jets, navy and air defence systems, he said.

Testing

Exports of military goods and technology from Russia came to more than $15.5 billion (€14bn) in 2014. With or without a deal, Iran's military is close to producing armour-piercing weapons made from either natural or depleted uranium, an ability shared by fewer than 20 countries worldwide, Karl Dewey, a London-based analyst said.

"They're not a game-changer but they're a potent capability," Dewey said.

Iran is probably already testing armour-penetrating weapons systems, possibly using uranium metal, according to Robert Kelley, a former director of the UN atomic watchdog and an ex-US nuclear weapons scientist.

"It's not the U.S. negotiating with Iran," Gary Sick said. "I think we're negotiating with the Russians. Although it's a touchy issue, I doubt it will be a deal-breaker."

Irish Independent