With just six days before the deadline, Iran's nuclear talks seem to be faltering as U.S. Secretary of State John Kerry arrived in Vienna on Sunday. 
 
 Kerry had his work cut out for him. As he worked to mend ties with Germany in its espionage dispute with the U.S. and handle the ongoing crisis in Israel and Gaza, Kerry also took on face-to-face meetings with his Iranian counterpart Mohammad Javad Zarif with a ticking clock behind them. By the day's end, no breakthrough had been produced and representatives from the six countries negotiating with Iran said that big hurdles remained. 
 
 The expiration of the interim deal 
 
 After decades of tense relations and mistrust, Iran and the United States (as part of the P5+1 Group) surprised the world by managing to secure an interim deal last fall that would ease sanctions on the Islamic Republic in exchange for suspending work on its nuclear program. July 20 was the date set for the deal to expire. And here we are. 
 
 While there have been some slight hints that discussions could extend beyond the deadline, the P5+1 group seems keen on getting a deal done by July 20. 
 
 As the Associated Press noted: 
 
 Lower-ranking officials represented both Russia and China, possibly reflecting their view even before Sunday that talks past July 20 are unavoidable. But Iranian Deputy Foreign Minister Abbas Araghchi suggested any extension would be relatively short, saying "there is not much willingness" by either side to go a full six months. He, too, earlier spoke of "huge and deep differences." 
 
 "There is a huge gap" 
 
 As reported, several gaps remain between the six countries and Iran, including major questions about the level to which Iran can enrich its uranium. Today, things got interesting. 
 
 Word started to spread about a speech given several thousand miles east of Vienna, in which Iran's Supreme Leader Ayatollah Ali Khamenei emphasized the need for Iran to enrich its uranium capacity at the very moment that the Iranian nuclear delegation and the P5+1 Group were bargaining to reduce it. 
 
 As the news broke, the words "scuttle" and "undermine" began floating: 
 
 Basically looks like Khamenei cut Zarif and co at the knees: http://t.co/9CMVgKD6dX — Jordan Hirsch (@jordanchirsch) July 14, 2014 
 
 Classic Khamenei: 1) Express support for negotiations 2) Undermine negotiators by setting impossible red lines. http://t.co/7dhb5BIzO9 — Karim Sadjadpour (@ksadjadpour) July 14, 2014 
 
 Does Iran want a deal? 
 
 Are these negotiating tactics or reluctance? As Gerald Seib points out (paywall), while the U.S.-led sanctions imposed by the international community had a pretty devastating bite, all the jockeying in Vienna is for naught if Iran doesn't want a deal: 
 
 But there is a difference between wanting a deal and considering one essential. Would economic relief be simply convenient, or does Iran consider failure to achieve it an existential threat to the regime? The negotiations won't succeed unless Iran wants a deal more than its international interlocutors do. And there's probably no way to know for sure exactly how much urgency Iran attaches to a deal until talks reach their 11th hour. 
 
 We'll find out soon enough. ||||| Image copyright Reuters Image caption The sides are carrying on talking after having missed several self-imposed deadlines 
 
 Iran's foreign minister has accused world powers of making it harder to reach agreement at nuclear talks in Vienna by taking different positions. 
 
 Mohammad Javad Zarif said "several countries" were also making "excessive demands". His UK counterpart said the process was proving "painfully slow". 
 
 The so-called P5+1 - US, UK, Russia, France, China and Germany - said talks would go on until at least Monday. 
 
 The powers suspect Iran of seeking nuclear weapons, which Iran denies. 
 
 Iran says its nuclear programme is for purely peaceful purposes. 
 
 The sides have been holding marathon negotiations to reach a long-term agreement and have missed successive self-imposed deadlines. 
 
 Both Mr Zarif and US Secretary of State John Kerry said though that they would not be rushed into making a deal. 
 
 "We're here because we believe we are making real progress," John Kerry told reporters on Thursday. 
 
 But he cautioned that "we are not going to sit at the negotiating table forever" and that he was prepared to "call an end" to nuclear talks with Iran if "tough decisions" are not made." 
 
 Media playback is unsupported on your device Media caption Iranians describe how they hope life will become more affordable if sanctions are lifted. 
 
 The failure to reach a deal by Friday means the US Congress will now take twice as long - 60 days - to decide whether to accept or reject any eventual deal, keeping sanctions in place until then. 
 
 Mr Zarif said late on Thursday that the negotiating position of the P5+1 was making it harder to reach a deal. 
 
 "Unfortunately we have seen changes in the position and excessive demands... by several countries," he said. 
 
 The sides have continued talking long past a self-imposed 30 June deadline to turn a framework deal into a comprehensive, final agreement. 
 
 Media playback is unsupported on your device Media caption Iran has the world's fourth largest crude oil reserves: 150 billion barrels 
 
 The P5+1 and Iran are working on a deal which will curb Iran's nuclear programme in return for sanctions relief, though the pace of the lifting of sanctions has been a major sticking point. 
 
 Analysis: BBC's Lyse Doucet, Vienna 
 
 Another deadline was missed - but no side in this marathon is calling it a bad sign. Negotiators emphasise how far they have come, how close they are. 
 
 But at this 11th hour there are, unsurprisingly, conflicting views on the impasse. Western diplomats speak of a small number of political and technical issues to resolve and place the onus on Iran. 
 
 But a senior Iranian official lamented that Iran now feels it is in five bilateral negotiations since every country has different "red lines." A senior Iranian official would only speak "of certain changes in the US position" as well as "a walking back" by other countries - they deny that. 
 
 It is clear more time is needed - but how much is not clear to anyone. An Iranian official said this wasn't "the 11th hour, but 13th or 14th". This is a process which, from the start, has had a clock all its own. 
 
 The P5+1 and Iran are still believed to differ in three key areas - international inspections of Iran's non-nuclear sites, sanctions relief, and how Iran's compliance will be verified. 
 
 Iran also wants a UN Security Council arms embargo to be scrapped - something the US has ruled out.
– A Sunday deadline is looming for Iran to strike a nuclear deal with six world powers under a plan set in motion last year—but with just days to go, Iran's supreme leader has made the chances of a deal being forged in time look supremely unlikely. In a major speech, Ayatollah Ali Khamenei said the country will need 190,000 centrifuge machines, 19 times as many as the 10,000 negotiators from the US, France, Britain, Russia, China, and Germany want to limit the country to in order to reduce its capacity to build nuclear weapons. After the leader's speech appeared to undermine negotiators, analysts began to wonder whether Iran really wants a deal that would limit its nuclear capacity in return for the lifting of sanctions, or if Khamenei is playing for time, the Atlantic notes. "In ostensibly expressing support for the Iranian negotiating team, close scrutiny of Khamenei's speech shows that in reality his remarks were aimed at severely curtailing his team's room for maneuver, making it effectively impossible to bridge gaps with the stance" of the six powers, an intelligence analysis seen by Reuters states. If all sides agree, the talks could be extended for another six months, though US officials say they will need to see some progress in the days to come before they will agree to an extension. John Kerry joined the talks in Vienna yesterday, but it's not clear whether he made any progress during hours of talks with Iran's foreign minister; issues including Afghanistan were also discussed, the AP reports.