The chairman of the US Joint Chiefs of Staff says he is "extremely concerned" about indications the Taliban is moving ever closer to Islamabad. Discussing the situation in an interview broadcast Friday on NBC's "Today" show, Adm. Mike Mullen said he believes "we're certainly moving closer to the tipping point" where Pakistan could be overtaken by Islamic extremists. Mullen said from Afghanistan he thinks that "events continue to move in the wrong direction" in both Pakistan and Afghanistan. And he said he hopes the arrival soon of an additional 17,000 American combat troops will stabilize things. Mullen said, "We're going as fast as we can go right now and we want to get it right." But he also said the Afghan people "have to take over security for their nation. That's the only way we're going to be successful."