US President Barack Obama has reaffirmed his plans to start withdrawing U.S. forces from Afghanistan in 2011 saying United States and its allies can't be there in perpetuity. Speaking in an interview with Australian television broadcast Thursday, the US President said that he did not agree that the situation in Afghanistan was getting worse, adding the Taliban's momentum had been blunted since he came to office. He, however, added that winning the nearly nine-year-old war remained a difficult task. The US President while announcing to send 30 thousand extra troops last December, had also announced phased withdrawal of its forces from July next year. Mr. Obama expressed confidence that Afghan President Hamid Karzai can stabilize his war-torn nation saying he is capable of leading his country into the 21st century. The US President said Washington would continue to press Afghan President to introduce essential reforms to improve living standards. Obama said the United States was not in Afghanistan to support one man, but to secure U.S. national security. His comments came in wake of Afghan President’s criticism early this month of US role during last year Presidential elections.