The poster for the recent George Clooney film Syriana, a tale of complex intrigue surrounding a fictional oil emirate, shows a bound and blindfolded CIA agent with the words “Everything is connected” emblazoned on the duct tape that gags him. The movie is a confusing pastiche, but that adage is worth remembering, especially when considering the ongoing crisis over Iran’s nuclear program.

For almost four years now, efforts by Europe and the United States to curb Tehran’s nuclear designs have vacillated between threats and appeasement. In February, after much intense, highly publicized diplomacy by Britain, France, Germany, and the United States, the board of governors of the International Atomic Energy Agency (IAEA)—including Russia and China—was persuaded to report Iran to the U.N. Security Council. The move seemed to raise the threat of sanctions, yet all parties were quick to call such talk premature. As diplomacy continued, so did the pace of Iran’s nuclear research, opening the prospects for chronic confrontation that could last years with no clear resolution.

Why the hesitation to take stronger action? One reason is certainly that China and Russia have been reluctant partners in the business of pressuring Tehran. China expects to sign long-term agreements for Iranian oil worth an estimated $100 billion. Russia is building nuclear reactors in Iran for which it is receiving billions of dollars as well. But the West, including the United States, has an even stronger and more direct incentive to talk instead of act: Any misstep in the campaign to deter Iran from developing nuclear technology that might be used for an atomic bomb could lead to an explosion in the...