In a report scheduled for release on Wednesday, the U.N. Atomic Energy Agency says Iran has put 1,008 advanced centrifuges under vacuum. Such a step is usually the last move before the uranium gas can be used as either reactor fuel or put in the core of a nuclear warhead. Iran has been using over 15,000 older machines for this same process, but these new centrifuges work up to four times faster. Iran still claims that it enriches uranium for peaceful purposes only.

This U.N. report focuses solely on a period when Mahmoud Ahmadinejad was still Iran’s president, before Hasan Rouhani took office. While many hope that President Rouhani, viewed by some as moderate, will improve relations with the West by curbing Iran’s nuclear program, Iranian Supreme Leader Ayatollah Ali Khamenei remains the country’s ultimate authority.