US President Barack Obama paid tribute to those who died in September 11th terror attacks 10 years ago and those who tried to save their lives. President Obama and his wife Michelle visited Arlington National Cemetery, paying their respects to US military personnel who died in the wars in Iraq and Afghanistan. They comforted others who were visiting the grave sites. The President also said the United States is stronger than it was ten years ago, and that al-Qaida, which conducted the attacks, is on the path to defeat.