Russian Foreign Minister Sergei Lavrov made it clear Thursday that Moscow wouldn't back any new rounds of tough sanctions against Iran in the United Nations Security Council, and he dismissed a U.S. timetable for securing progress from Iran on ending its nuclear-fuel program.

Mr. Lavrov's comments in Moscow led U.S. officials to acknowledge that new U.N. sanctions against Iran were now unlikely in the near term -- endangering a major element of President Barack Obama's high-profile strategy for diplomacy in the Middle East. "We're pretty disappointed with the Russian position so far," a senior U.S. official said.
The development also appeared a blow to hopes that the Obama administration's "reset" of relations with Russia would lead to Moscow supporting a top U.S. foreign-policy priority.
Just a day after U.S. officials warned that Iran may already have enough enriched uranium to make a bomb if processed further, Mr. Lavrov said negotiations should begin without any imposed timetable. He also said that even if Iran tried to make weapons-grade fuel it would be detected and there would be time to respond. "I do not think those sanctions will be approved by the United Nations Security Council," Mr. Lavrov said.