US Secretary of State Condoleezza Rice began talks with European and Russian officials on Thursday to urge greater international pressure on Iran to halt uranium enrichment and answer questions about its nuclear programs. Days after a new US intelligence estimate contradicted years of assertions that Iran is secretly pursuing atomic weapons, Rice was stressing with NATO allies and Russia the US case for continued isolation of the Iranian regime. Rice said she would argue during the two days of meetings for more pressure. It is her first face-to-face sessions with world powers now considering new UN sanctions on Iran over its nuclear program since the National Intelligence Estimate was released on Monday. "I don't see that the NIE changes the course that we're on," Rice told reporters aboard her plane as she flew to Belgium for a conference of NATO foreign ministers and talks between the alliance and former Cold War foe Russia, which, along with China, has been particularly resistant to new sanctions. "In fact, I would think given the assessment that Iran is indeed susceptible to coordinated international pressure that (this) is the right approach," she said, referring to the NIE finding that Iran halted its nuclear weapons program in 2003 due to intense diplomatic activity. "The point that I'm emphasizing to people is that it was international pressure that got the Iranians to halt their program," she said. "This suggests that you ought to keep up that international pressure." Rice was to meet separately on Thursday with the foreign ministers of Italy, Belgium and Britain as well as European Union foreign policy chief Javier Solana and NATO Secretary-General Jaap de Hoop Scheffer. Iran will be a major topic in all of those discussions as well as in Rice's Friday talks with Russian Foreign Minister Sergey Lavrov, perhaps the figure most suspicious of the US policy on Iran, and German Foreign Minister Franck-Walter Steinmaier, whose government appears conflicted on the matter. Rice will also see Israeli Foreign Minister Tzipi Livni on Friday. Israeli officials say their intelligence forces believe Iran is still working aggressively to build nuclear arms despite the new US conclusion about Iran. The Islamic regime in Tehran is strongly opposed to Israel's existence and frequently boasts of its ability to strike the Jewish state with long-range missiles. Bush administration officials have conceded that their abrupt abandonment of that point will likely hurt their efforts to impose more sanctions on Iran to increase pressure for it to cease uranium enrichment and reprocessing, which could produce the ingredients for a bomb. "Perhaps, but it wasn't easy to begin with," Vice President Dick Cheney said Wednesday in an interview with Politico.com, an online political magazine. Discussions on that point, between the US and the other permanent members of the UN Security Council - Britain, France, Russia and China - plus Germany in the so-called "P5+1" grouping are now on hold pending consideration of the new intelligence. Whatever assessments are made, Rice said she would impress on her counterparts the need for Iran to disclose the nature of its alleged secret nuclear weapons program prior to 2003, returning to a theme addressed by US President George W. Bush. "We should also start to look at ways for Iran to account for what was happening before 2003," she said, without elaboration on what type of mechanism she had in mind, if any. Bush on Wednesday demanded that Tehran detail its previous program to develop nuclear weapons, "which the Iranian regime has yet to acknowledge." "The Iranians have a strategic choice to make," he said in Nebraska. Iranian President Mahmoud Ahmadinejad proclaimed that the new assessment is "a declaration of victory for the Iranian nation against the world powers over the nuclear issue." Rice scoffed at those remarks but has been working the phones to defend the administration's surprise shift on Iran and to explain it to those in the international community who have been calling for diplomacy. "It opens a window of opportunity for Iran now, because Iran obviously has been somewhat vindicated in saying that they have not been working on a weapons program, at least for the past few years," UN International Atomic Energy Agency chief Mohamed ElBaradei said. Rice also said Thursday that US plans to deploy a missile defense system in former Soviet satellite states in central Europe can be refined to suit Russian concerns. Her statement came a day after Lavrov accused the United States of backtracking on missile defense issues. "There has been a serious rollback from what we were told," Lavrov said, referring to a meeting he had with Rice in October. Speaking to reporters on the way to a NATO meeting in Brussels, Rice said that as details emerge on the US plan "perhaps there are things the Russians thought might be there that are not there." She said the United States was willing to discuss these details, adding "there is no reason to assume that there isn't room to continue to refine these proposals." Lavrov said in Moscow Wednesday the United States has withdrawn a proposal for constant Russian monitoring of planned US missile defense facilities in Poland and the Czech Republic and has rejected the idea of jointly evaluating threats that would trigger an activation of the system. The United States says the installations in the two nations - now NATO members - would counter a looming Iranian threat. Moscow disputes Washington's view of that threat and says it believes the real aim is to weaken Russia.