Decisions by the foreign ministers of Russia and China to skip talks on Iran's nuclear program this weekend are further denting expectations that the stalled negotiations will produce a deal by July 20.



The U.S. - which is sending Secretary of State John Kerry to join three other ministers- is putting on a good face. State Department spokeswoman Marie Harf says the six powers talking with Iran remain “united in the negotiating room, as we always have.”



But the absence of Russian Foreign Minister Sergey Lavrov is noteworthy, in light of suggestions by France that Moscow is deviating from joint negotiating stances with Iran. It may also reflect recognition that the two sides are too far apart, and the talks will have to be extended.



The most important disputes over how deeply Iran must cut its nuclear program to gain sanctions relief are between Washington and Tehran, so Kerry's presence is important. He will be able to talk directly to Iranian Foreign Minister Mohammad Javad Zarif, who is already at the Vienna negotiations.



British Foreign Secretary William Hague, French Foreign Minister Laurent Fabius and German Foreign Minister Walter Steinmeier are also attending. But the absence of Lavrov and Chinese Foreign Minister Wang Yi could be detrimental - it took foreign ministers or their deputies of all six nations to negotiate a preliminary deal with Tehran in November.



Lavrov is on a Latin American tour culminating with a July 15 Brazil summit of emerging major economic nations, including China. Still, his no-show comes at a troubling moment - just days after Fabius criticized Moscow for having “differences of approach” with the mainstream at the negotiations.



The French foreign minister didn't elaborate. But Kremlin-backed analysts blame the U.S. for stalling the talks by pushing unrealistic demands.



Vladimir Evseyev of the Russian state-run CIS institute says Washington's insistence that Iran shut down uranium enrichment facilities and negotiate on its missile program violates the accords outlining the scope of the talks. The U.S., he said, wants negotiations to “to be lengthy and painful,” so as to keep sanctions in place for its own political agenda.



Diplomats familiar with the talks say Moscow shares Washington's desire to reach a deal but is significantly less demanding of Tehran. While the U.S. wants deep cuts in Iranian programs that could be used to make nuclear arms, Russia would settle for pervasive monitoring, they say.



Former U.S. State Department official Mark Fitzpatrick says the Russian absence might simply indicate that Moscow doesn't anticipate agreement by July 20.



But “if a deal does appear to emerge, I wouldn't be surprised to see Lavrov on the next plane to Vienna,” says Fitzpatrick, now with the International Institute for Strategic Studies in London.



Last Update: Saturday, 12 July 2014 KSA 12:30 - GMT 09:30