Definition: In this task, you will be presented with a passage and have to answer a question based on your understanding of the events inferred from the passage. Try to find the best answer that is most likely to fill in "_". Note that the URLs in the text have been replaced with [Link].
Input: United Nations (CNN) -- Delegates from the United States and other nations walked out of the U.N. General Assembly on Thursday as Iranian President Mahmoud Ahmadinejad delivered a fiery speech that criticized Washington, capitalism and the world body itself. Though incendiary statements from Ahmadinejad are nothing new, tension in the hall grew as the Iranian leader recounted various conspiracy theories about the September 11, 2001, terrorist attacks on New York and Washington. "Some segments within the U.S. government orchestrated the attack," Ahmadinejad told the General Assembly. He followed with the claim that the attacks were aimed at reversing "the declining American economy and its scripts on the Middle East in order to save the Zionist regime. The majority of the American people, as well as most nations and politicians around the world, agree with this view."NEW: Obama found the speech "outrageous and offensive," the White House saysMahmoud Ahmadinejad's address included 9/11 conspiracy theoriesDelegates from U.S., Britain, Sweden, Australia and Spain walked out on the speechThe Iranian president also linked wars in Iraq and Afghanistan to colonial expansion 
 Question:President Barack Obama already had delivered his address to the _ and had left the grounds before Ahmadinejad spoke.

U.N. General Assembly