In reciprocation for Iran's "concrete actions, " the United States and its P5 plus 1 partners -- Britain, France, Germany, Russia and China, as well as the European Union (EU) -- will today follow through on their commitment to begin to provide modest sanctions relief for Iran, White House press secretary Jay Carney announced on Monday."At the same time, we will continue our aggressive enforcement of the sanctions measures that will remain in place throughout this six-month period, " Carney said in a statement released by the White House.Today, the International Atomic Energy Agency (IAEA) reported that Iran has taken the initial specific steps it committed to on or by Jan. 20 as part of the Joint Plan of Action between the P5 plus 1 and Iran, Carney said, adding, "As a result, implementation of the Joint Plan of Action will begin today." Specifically, the IAEA has verified in a written report and subsequent briefing for P5 plus 1 technical experts that Iran has, among other things, stopped producing 20 percent enriched uranium, has disabled the configuration of the centrifuge cascades Iran has been using to produce it, has begun diluting its existing stockpile of 20 percent enriched uranium, and has not installed additional centrifuges at Natanz or Fordow, Carney said. "These actions represent the first time in nearly a decade that Iran has verifiably enacted measures to halt progress on its nuclear program and roll it back in key respects," he said. Iran has also begun to provide the IAEA with increased transparency into the Iranian nuclear program through more frequent and intrusive inspections and the expanded provision of information to the IAEA, Carney said."Taken together, these concrete actions represent an important step forward, " he said.Following the actions taken today, the P5 plus1, EU and Iran will also begin the process of negotiating a long-term, comprehensive solution that seeks to address the international community's concerns about Iran's nuclear program, Carney said."The United States remains committed to using strong and disciplined diplomacy to reach a peaceful resolution that will prevent Iran from obtaining a nuclear weapon," he said.