was the first time a sitting president has been a guest on the popular late-night entertainment show, according to the CBS Web site.
After taking the stage to a huge ovation, Obama teased Letterman about being surprised to see the event on his daily schedule, saying: "That's one of those where you ask your advisers, 'who's responsible for this?' "
Later, when talking about summer activities of daughters Malia, 11, and Sasha, 8, Obama said that they "goofed off," which he added was something he couldn't do. Letterman quickly quipped: "Well, you have," prompting a big laugh from both the audience and the president.
On topical issues, Obama promised to ask "tough questions" before deciding whether to send additional U.S. troops to Afghanistan, saying it was necessary to have a clear strategy in place before deploying resources.