Iran will send its nuclear material to Turkey, marking a major diplomatic breakthrough in the standoff with Tehran over its nuclear program, which the country says is for peaceful uses but many nations worry is intended to build a nuclear weapon. Brazilian and Turkish officials brokered the deal during a marathon 18-hour session in Tehran Sunday. The Iranian foreign minister announced that the International Atomic Energy Agency would see the paperwork within a week, after which Iran will ship its fuel to Turkey. (The deal is similar to one proposed by the Obama administration last year, though the intermediary was to have been Russia. Uranium enriched to 3.5 percent will be sent to Turkey in exchange for 20 percent enriched uranium from the IAEA, the minister said.) Iranian President Mahmoud Ahmadinejad called on the U.S. to reenter talks with Tehran “based on honesty, justice and mutual respect.” White House Press Secretary Robert Gibbs responded today, calling Iran’s deal a “positive step” but that the U.S. still has “serious concerns” about its nuclear program.