THE report on Iran's nuclear capabilities that the IAEA will release this week is, at least for what the Washington Post reports, worrying:

Intelligence provided to U.N. nuclear officials shows that Iran’s government has mastered the critical steps needed to build a nuclear weapon, receiving assistance from foreign scientists to overcome key technical hurdles, according to Western diplomats and nuclear experts briefed on the findings.

Documents and other records provide new details on the role played by a former Soviet weapons scientist who allegedly tutored Iranians over several years on building high-precision detonators of the kind used to trigger a nuclear chain reaction, the officials and experts said. Crucial technology linked to experts in Pakistan and North Korea also helped propel Iran to the threshold of nuclear capability, they added.

The officials, citing secret intelligence provided over several years to the International Atomic Energy Agency, said the records reinforce concerns that Iran continued to conduct weapons-related research after 2003 — when, U.S. intelligence agencies believe, Iranian leaders halted such experiments in response to international and domestic pressures.

The U.N. nuclear watchdog is due to release a report this week laying out its findings on Iran’s efforts to obtain sensitive nuclear technology. Fears that Iran could quickly build an atomic bomb if it chooses to has fueled anti-Iran rhetoric and new threats of military strikes. Some U.S. arms-control groups have cautioned against what they fear could be an overreaction to the report, saying there is still time to persuade Iran to change its behavior.