By Caren Bohan PITTSBURGH, Sept 25 (Reuters) - U.S. President Barack Obama said on Friday he understands Americans' impatience with the Afghanistan war and vowed to ask tough questions of his advisers as he weighs whether to send more troops there. A Gallup poll released on Friday said 50 percent of Americans opposed sending more troops to Afghanistan while 41 percent supported it, a drop in backing for the eight-year war begun after the Sept. 11 attacks. "This is not easy, and I would expect that the public would ask some very tough questions," Obama told a news conference at the Group of 20 economic summit in Pittsburgh. "That's exactly what I'm doing, is asking some very tough questions." Gen. Stanley McChrystal, the top U.S. and NATO commander in Afghanistan, is expected by Saturday to submit a formal request for additional troops to the Pentagon next year. Administration and congressional sources had expected him to seek at least 30,000 more troops and trainers for next year. Earlier this week, a confidential assessment of the war was leaked to the media in which McChrystal warned that the U.S.-led mission was likely to fail without more troops. But Obama has said he wants to determine the proper strategy for U.S. forces in Afghanistan before considering whether more troops should be sent there. Republicans have criticized him for delaying the decision. In Pittsburgh, Obama said questions about the credibility of August's Afghan elections were a serious concern. "What's most important is that there is a sense of legitimacy in Afghanistan among the Afghan people for their government," Obama said. "If there is not, that makes our task much more difficult." "With respect to public opinion, I understand the public's weariness of this war, given that it comes on top of weariness about the war in Iraq," Obama said. Obama reiterated that the overriding mission of the U.S. efforts in Afghanistan and Pakistan was to defeat al Qaeda. In Afghanistan, he said that much of the success is "linked to the ability of the Afghan people themselves to provide for their own security" and the Afghan government's ability to provide services for its people. "I will ultimately make this decision based on what will meet that core goal that I set out at the beginning, which is to dismantle, disrupt and destroy the Al Qaeda network," he said. In addition to sending more troops, the White House is considering alternatives such as mounting more aerial and commando strikes against al Qaeda and Taliban targets in neighboring Pakistan, officials said. The White House may also opt to do both simultaneously. (Editing by Doina Chiacu)
A man sits on top of his family's belongings, which are loaded on a truck, while fleeing Pakistan's Khyber tribal region, in the town of Bara September 25, 2009. Hundreds of ...
