Originally posted by the Voice of America. Voice of America content is produced by the Voice of America, a United States federal government-sponsored entity, and is in the public domain. Iran Unveils More Powerful Centrifuges VOA News 09 April 2010 Iran's President Mahmoud Ahmadinejad, after unveiling a third generation of domestically built centrifuge, 09 Apr 2010 Photo: AP Iran's President Mahmoud Ahmadinejad, after unveiling a third generation of domestically built centrifuge, 09 Apr 2010 Iran's president unveiled a new generation of centrifuges used to enrich uranium Friday, defying international warnings against continuing its sensitive nuclear work. Mr. Ahmadinejad displayed one of the new, domestically-built machines Friday, saying international efforts to pressure Iran on its nuclear program will be met with even more resistance.  The announcement marked Iran's National Nuclear Day. Also Friday, U.S. President Barack Obama said there is no guarantee that new U.N. sanctions will persuade Iran to change course. However, he added, with "consistent and steady" international pressure, Iran may eventually realize pursuing nuclear weapons is not worth the cost. During an interview with ABC news, Mr. Obama said Iran is "not a stupid regime" and is intently watching what is happening in the international community. Thursday, six world powers began negotiations on a possible new round of U.N. Security Council sanctions against Tehran for its nuclear activities.  The world powers are Germany and the five permanent council members - the United States, Britain, France, Russia and China. Iranian state media reported Friday that the new centrifuges are twice as powerful as its older ones. The centrifuges are used to spin uranium gas at extremely high speeds, causing its more purified elements to separate from the rest. The process can be used to produce weapons-grade nuclear material. World powers believe Iran is secretly trying to develop nuclear weapons, a charge it denies. Some information for this report was provided by AFP and AP. .