The top US military commander was expected to travel to Pakistan's lawless border region on Sunday, a day after he said the threat of Islamic extremism was growing in the country. Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, was expected to travel to the city of Peshawar to meet with commanders of the Pakistani 11 Corps, which is fighting in the border area. Mullen met Saturday with Pakistan's senior leadership, including President Pervez Musharraf and army chief Gen. Ashfaq Parvez Kayani. Mullen said much of the discussion centered on the situation along Pakistan's northwestern border with Afghanistan, where Pakistani forces have been battling Taliban and al-Qaida fighters. "Certainly the threat is going up," Mullen said. "We're both concerned about that. Certainly in my meetings today, all the leadership expressed concern about being able to eliminate that threat over time."