VIENNA - Iran has taken steps in recent weeks that bring it closer to launching uranium enrichment deep inside a mountain, diplomatic sources say, a move that would worsen its nuclear confrontation with the West.Iran has said for months that it is preparing to conduct uranium enrichment at Fordow - a protected site deep underground where it says it wants to make material for a peaceful nuclear reactor - but it has yet to start.RELATED:EU governments consider delay on any Iran oil banIran plans new military maneuvers in FebruaryThe West suspects it of seeking the enriched uranium for a bomb, and wants it to halt the plans. Were Iran to begin production at the site, near the Shi'ite Muslim holy city of Qom, it could make it harder to revive nuclear talks that collapsed a year ago.Western countries have imposed increasingly tight economic sanctions on Tehran over its nuclear program, culminating with a new law signed on New Year's Eve by US President Barack Obama aimed at preventing buyers from paying for Iranian oil.One Vienna-based diplomat said Iran was believed to have begun in late December feeding uranium gas into centrifuges as part of final preparations to use the machines for enrichment."They are close to being able to begin enriching," the diplomat said. "They have to do some experimenting and refining to get it right."An official of another country said he believed Iran was carrying out "passivation," a technical step involving putting nuclear material into the centrifuges to prepare them to be activated for enrichment. "I would assume they could start if they wanted to," he said.Apart from the technical question of preparing Fordow for launch, Iran would have to take a political decision to start enrichment there. Western capitals may be hoping that the latest sanctions, which are imposing real pain on the Iranian economy, would persuade Tehran to hold off.Iran is already refining uranium to a fissile purity of 20 percent - far more than the 3.5 percent level usually required to power nuclear energy plants - above ground at another location.It is moving this higher-grade enrichment to Fordow in an apparent bid to better protect the work against any enemy attacks. It also plans to sharply boost output capacity.The machines and other equipment needed to start enrichment were installed at Fordow last year.The United States and Israel, Iran's arch foes, have not ruled out strikes against the Islamic state's nuclear sites to prevent it from acquiring atomic arms. Iran says its nuclear program is peaceful, mainly for generating electricity.Iran's mission to the International Atomic Energy Agency, the Vienna-based UN nuclear watchdog and the IAEA itself were not available for comment. UN inspectors regularly visit Iranian nuclear facilities, including the one at Fordow, and track developments there.