The U.N.'s nuclear watchdog is expected to report this week that Iran has mostly cooperated with an investigation of its nuclear program's murky past, but that key questions remain unanswered, diplomats say.
The European Union's nuclear negotiator, Javier Solana, is likely to confirm this month that Iran has not suspended uranium enrichment as demanded by the Security Council, opening the door to tougher sanctions.
But without a clear-cut judgment that Iran is pursuing a nuclear weapon, the council may find itself in the same position it has been in the last four years: unable to compel Iran to suspend its nuclear program until Tehran can prove it is solely for producing energy.
"Iran may have walked that tightrope well enough to keep things going," said a Western diplomat in Vienna, where the United Nations' International Atomic Energy Agency is based.
The United States, Britain and France are circulating their own set of questions about Iran's uranium enrichment to highlight how much is unknown about the country's nuclear intentions, past and present, according to the Associated Press, which had obtained the 10-page document.
"We have a whole range of outstanding questions about Iran's nuclear program," Britain's ambassador to the U.N., John Sawers, said Wednesday.
In an effort to show its cooperation before IAEA chief Mohamed ElBaradei's report, which is expected today, Iran handed over a long-withheld blueprint showing how to shape uranium metal into hemispheres for a nuclear warhead, dipIomats said.
IAEA inspectors had discovered the document in 2005 but were permitted only to read it and not take it outside the country. The Iranians have said it was given to them unsolicited by Pakistani scientist Abdul Qadeer Khan, known as the father of Pakistan's atomic bomb, who secretly peddled nuclear technology to Iran, Iraq, North Korea and Libya.
Iranian officials said they did not try to manufacture a weapon from the plans. ElBaradei had demanded the document as part of a "plan of work" that requires Iran to answer questions one by one about its two decades of clandestine nuclear development. ElBaradei has said he hopes to finish the inquiry by the end of the year.
Iran also provided information about P1 and P2 centrifuges designed to enrich uranium, said Iran's deputy foreign minister, Abbas Araghchi, after meeting with British lawmakers Tuesday in London.
The P2 type, believed to operate with technology provided by Khan, is more sophisticated and can refine uranium two or three times faster than the P1.
Last week, Iranian President Mahmoud Ahmadinejad said that a cascade of 3,000 centrifuges was operating and that Tehran's nuclear program was irreversible. If the cascade is functioning properly, it can enrich enough uranium for a bomb in about a year, scientists say, though U.S. intelligence estimates put Iran between four and seven years away from constructing a complete weapon.
The United States will keep pushing for harsher sanctions, even if the IAEA reports partial cooperation by Iran, Gregory L. Schulte, the U.S. envoy to the IAEA, said Wednesday.
The U.S., Britain and France have been pressing the other two permanent members of the Security Council, China and Russia, to increase targeted penalties on officials and companies involved in the nuclear program unless Iran suspends enrichment.
The Chinese and Russian foreign ministers have visited Tehran in the last two weeks to encourage cooperation with the IAEA. The two countries are key trade partners with Iran.
Although Moscow and Beijing have voted for sanctions against Iran before and have agreed to prepare further penalties in case this month's IAEA and EU reports are negative, they are expected to argue that sanctions would derail Iran's improved cooperation.
"As long as the process moves a bit forward, we should keep on this track," a Chinese diplomat said. "The main thing for the Security Council is to help the IAEA answer these outstanding questions, and we are not convinced that additional sanctions would help."
But the U.S. made it clear that a bit of progress was not what it was seeking.
"Selective cooperation is not good enough," Schulte told reporters in Vienna. "When we read this report and evaluate Iran's cooperation, the standard we will look for is full disclosure and also a full suspension of their proliferation-sensitive activities."