Limits of Trust

Russian President Putin may not have won an agreement with President Bush on missile defense, but he did get something else--besides kind words--during last week's summit: an unprecedented intelligence briefing from CIA chief George Tenet. Presidential chief of staff Andrew Card says the U.S. appreciates Russia's cooperation in the war against terror, and the briefing was intended partly "to acknowledge and thank President Putin." But trust has its limits. Left out of the briefing were specific details of Iran's efforts to obtain nuclear weapons. That seems strange, since the U.S. is unhappy that Russia is selling nuclear power equipment to Tehran--and Russia says it needs proof of Iran's nuclear ambitions before it will consider stopping. But U.S. intelligence officials still fear that sharing the information could reveal too much about U.S. intelligence-gathering capabilities. Meanwhile, the Izhora factory in St. Petersburg, Russia, just completed a 317-ton reactor component bound for Iran's Bushehr nuclear power plant, the first one to be delivered under a 1995 pact worth $800 million.

--By Massimo Calabresi and John Dickerson