PARIS — Tensions between the West and Russia over events in Ukraine have cast a shadow over the second round of talks set to begin on Tuesday in Vienna on a permanent nuclear agreement with Iran.
Although the talks have no direct connection to Ukraine, their success hinges on solidarity among the so-called P5-plus-one countries — the five permanent members of the United Nations Security Council, which include Russia, plus Germany — in favor of a tough agreement with Iran to drastically scale back its nuclear program.
If Russia signals that its cooperation with the West has weakened, that will reduce pressure on Iran to make concessions, said experts knowledgeable about the talks, which began last month with three days of meetings involving senior diplomats from each of the governments involved.
A senior American official, speaking before the Iran talks and just before the secession vote in Crimea on Sunday that overwhelmingly approved reunification with Russia, indicated concern about possible consequences from the friction over Ukraine. Since western nations consider that vote illegal and have warned President Vladimir V. Putin of Russia not to annex Crimea, the situation for the Iran talks would now seem more worrisome.
“I think that we all hope that the incredibly difficult situation in Ukraine will not create issues for this negotiation,” said the official, speaking on the condition of anonymity because of the sensitivity of the talks.
“We hope that whatever happens in the days ahead, whatever actions we and the international community take, depending upon the decisions and the choices that Russia makes, that any actions that Russia subsequently takes will not put these negotiations at risk,” the official said.