in VOA Special English.This week, leaders of the top industrial and developing economies gathered in the eastern United States. They met in Pittsburgh, Pennsylvania, for a summit on the world's financial future. Leaders of the Group of Twenty have now met three times in less than a year to deal with the worst recession since the nineteen thirties.Many of their governments have used spending programs to inject five trillion dollars into their economies. These stimulus efforts have had some success. Now, the question is how and when to withdraw that support without harming a recovery, and how to avoid a repeat of the financial crisis.The leaders agreed to make the G20 the main group for their international economic cooperation, instead of the G8. The G20 is nineteen countries and the European Union. It includes fast-growing economies in the developing world like China, India and Brazil.Earlier this week, world leaders attended the United Nations General Assembly in New York. President Obama, in a speech on Wednesday, sought to distance himself from some of the policies of George W. Bush.BARACK OBAMA: "Those who used to chastise America for acting alone in the world cannot now stand by and wait for American to solve the world's problems alone. We have sought in word and deed for a new era of engagement with the world."On Thursday, the Security Council approved a resolution to increase efforts toward a world without nuclear weapons. All fifteen members voted for the resolution proposed by the United States.The five permanent members are the United States, Britain, China, France and Russia. Those five plus Germany have been preparing to meet with Iranian negotiators on October first to discuss Iran's nuclear program.On Friday, there were new demands for Iran to follow Security Council resolutions to halt nuclear enrichment. The American, British and French leaders announced that Iran has been secretly building a second enrichment center for several years.American officials say the information was made public after Iran discovered that Western intelligence agencies knew about the facility. Iran informed the International Atomic Energy Agency in Vienna earlier this week.Enriched uranium can be used as fuel for nuclear energy -- as Iran says -- or it can be used for nuclear bombs. French President Nicolas Sarkozy said, "If by December, there is not an in-depth change by the Iranian leaders, sanctions will have to be taken."In New York, Iranian President Mahmoud Ahmadinejad said President Obama will regret saying that Iran has been building a secret facility. He said Iran met I.A.E.A. rules by informing the agency early enough that the facility was being built. Russia and China both urged Iran to cooperate with the U.N. nuclear agency on any investigation.And that's IN THE NEWS in VOA Special English. For more news from the G20 meeting, go to 51voa.com.