Israeli Defense Minister Ehud Barak arrived in Washington this week with the message that not even the far-reaching sanctions adopted by the U.S. and its allies against Iran are likely to change Iran's behavior. "It's still time for sanctions," he told the Washington Post in an interview. But "probably, at a certain point, we should realize that sanctions cannot work." That assessment squares with one offered by CIA Director Leon Panetta in a recent TV interview: "I think the sanctions will have some impact ... Will it deter them from their ambitions with regards to nuclear capability? Probably not."

Barak's visit came as the European Union on Monday adopted far-reaching trade sanctions that included bans on investment in Iran's oil and gas sector, and British Prime Minister David Cameron on Tuesday urged Turkey to use its close ties with the Iranian regime to tell Tehran to change course. The Turks, while accepting their obligation to adhere to the U.N. sanctions against Iran that they opposed, have publicly refused to abide by the additional measures adopted by the U.S. and the E.U. Instead, they are expanding their trade ties with Iran to help fill the gaps left by the withdrawal of other partners.

Iran, meanwhile, is expected to resume talks in September with Western powers over a fuel-swap deal brokered by Brazil and Turkey shortly before the latest round of sanctions. That deal does not address the fundamental issues of the standoff, but it was designed as a confidence-building measure that could help change the increasingly confrontational dynamic over Iran's nuclear program.