In a toughly worded letter, European foreign ministers threatened Tuesday to cut off negotiations over Iran’s nuclear program if Tehran made good on its promise to resume uranium conversion. Meanwhile, Western intelligence on Iran’s nuclear program recently obtained by The Times indicates that the country may have agreed with the Europeans to suspend its uranium program in November 2004 only because the effort had been beset with technical difficulties. The Iranians may be seeking to restart the conversion program because they think the major problems have been solved, officials and analysts said. Full Story