The top U.S. military officer met with Pakistani military commanders in the North West Frontier Province Sunday.
Admiral Mike Mullen, the chairman of the Joint Chiefs of Staff, traveled to the provincial capital Peshawar to discuss Pakistani military efforts against al-Qaida and the Taliban in the region near Afghanistan.
His visit came a day after meetings with Pakistani President Pervez Musharraf and army chief Ashfaq Parvez Kayani in Islamabad.
The admiral said Saturday that the threat of Islamic extremism is growing in Pakistan.
The U.S. military chief noted the increasing number of suicide bombings in the country and said that such terrorist activity is a threat to both Pakistan and the United States.
Admiral Mullen also said he believes Pakistan's nuclear arsenal is secure, and that he is not concerned the nuclear weapons could fall into the hands of terrorists.
Mullen added the U.S. will always respect Pakistan's sovereignty and will continue to provide counter-terrorism training to Pakistan's military.
President Musharraf has rejected offers by U.S. defense officials to send U.S. troops into Pakistan to combat terrorists.
Some information for this report was provided by AFP and AP.