The US and Russia were at odds on Thursday over Teheran's proposals for negotiations with the West, with American officials saying they fall short of satisfying international demands, and the Russians saying there was something to talk about. Even as American officials warned that time was running out and dismissed the Islamic Republic's response as disappointing, Reuters reported Russian Foreign Minister Sergei Lavrov as saying that "based on a brief review of the Iranian papers, my impression is there is something there to use." Iran proposed a worldwide system aimed at eliminating nuclear weapons, President Mahmoud Ahmadinejad's top political aide said in an interview on Thursday with The Washington Post, but would not discuss halting its own uranium enrichment program. Iran also offered to help solve problems in Afghanistan, fight terrorism, and collaborate on oil and gas projects, Mojtaba Samareh Hashemi said. Israel, for its part, reiterated its position that Iran was doing little more than playing for time. "Israel's position is well known and has been expressed on many previous occasions in the past," said Yossi Levy, the Foreign Ministry's spokesman for the domestic press. "The Iranians have been trying for a long time to stall, and the world is obligated to stop them immediately. This is a historic crossroad for world peace." One US official familiar with the proposals submitted by Teheran on Wednesday said it reworked previous Iranian suggestions for talks with six nations - the US, Britain, China, France, Germany and Russia. The official said Iran's document, which it billed as a "Proposal for Comprehensive and Constructive Negotiations to Deal with International, Security and Economic Issues," did not address the US offer for engagement. The proposal also did not respond to the six countries' offer of concessions in exchange for a suspension of Iranian uranium enrichment and reprocessing. The Iranians made no mention of concerns about their nuclear program, the official said. "We're trying to evaluate what this means, what they are saying, and we are going to test them on whether they are serious about engagement," the official said. With a US-imposed September deadline for the Islamic Republic looming, American officials said the Obama administration remained open to talks and held out hope that Iranian officials might signal a similar interest by the time world leaders met later this month at the UN General Assembly. President Barack Obama warned Iran earlier this year that the US wanted to see a positive response to its overtures by the end of September. If not, Obama said the US was prepared to press for new sanctions against Iran. Senior diplomats from the six countries trying to launch negotiations with Iran spoke by conference call on Wednesday about its proposal and were to have a second round of talks on Thursday. The US officials said the administration would like to have a consensus by the time the foreign ministers of the six countries meet in New York on the sidelines of the UN General Assembly in the third week of September, when Obama is also slated to chair a meeting of the Security Council on nuclear nonproliferation. The officials said it was not clear when the group might decide how to proceed. Russia and China have in the past blocked attempts to impose additional sanctions on Iran. Lavrov indicated on Thursday that Russia would not back bans on refined oil exports to Iran. "Some of the sanctions under discussion, including oil and oil products, are not a mechanism to force Iran to cooperate - they are a step to a full-blown blockade and I do not think they would be supported at the UN Security Council," he said. These types of sentiments means the United States and its European allies may have to go forward with their own penalties outside the UN system. Prime Minister Binyamin Netanyahu addressed this possibility on his visit to Berlin two weeks ago, when - at a press conference with German Chancellor Angela Merkel - he talked about a "coalition of the willing" imposing crippling sanctions that could have "enormous impact" on Iran. Merkel was not convinced, saying it was important to get Russia and China on board, and that sanctions would be ineffective if they were taken only by the US and some European countries. Iranian state radio, reporting on the proposal on Wednesday, said that "Iran is ready to... help ease joint international concerns over the nuclear issue," but it did not elaborate. It said Teheran aims to reach a "comprehensive agreement based on collective goodwill to achieve long-term cooperation and strengthen regional and global peace and security based on justice." The state radio added that the package looks at issues "beyond the nuclear file," including crises in Iraq, Afghanistan, Lebanon and the Palestinian territories. But Iran's President Mahmoud Ahmadinejad has said his country would neither halt uranium enrichment nor negotiate over its nuclear rights. In Vienna, the headquarters of the UN nuclear watchdog, Glyn Davies, the chief US envoy to the International Atomic Energy Agency, said on Thursday that Washington sincerely hoped Iran would engage "constructively" and "specifically" over its nuclear program. A day earlier Davies said the United States assessed that Teheran was either very near or already in possession of sufficient low-enriched uranium to produce a nuclear weapon, if the decision were made to further enrich it to weapons-grade. Those comments were echoed on Thursday by a US intelligence official who said the administration continues to believe that Iran is on the path to developing a nuclear weapon, but has not yet made the decision to make one. The administration thinks Iran could have the capability to produce a nuclear warhead between 2010 and 2015. Similar assessments were made by senior Israeli officials and reported in The Jerusalem Post in early July. The US intelligence official said American knowledge of the Iranian nuclear program is expanding and new assessments have been shared with administration officials.