ISLAMABAD , Pakistan ( CNN ) -- The chairman of the U.S. Joint Chiefs of Staff arrived in Pakistan on Tuesday amid tensions between the two countries about U.S. military incursions into Pakistan 's tribal areas . Adm. Michael Mullen will meet with Pakistan 's new prime minister and its military chief . Adm. Michael Mullen will meet with Pakistan 's newly elected prime minister , Yousaf Raza Gilani , and Pakistan 's military chief , Gen. Parvez Kayani , Mullen 's office said . Relations between the United States and Pakistan have been tense since the U.S. military sent ground forces into Pakistan 's tribal regions earlier this month without Islamabad 's permission . The incident prompted the Pakistani government to summon the U.S. ambassador to voice its disapproval , as well as deliver a `` demarche '' ( a diplomatic petition or protest ) through its ambassador in Washington . Last week , Kayani announced no foreign forces will be allowed to conduct operations inside Pakistan in light of the `` reckless '' U.S. military ground operation . Kayani said Pakistan 's `` territorial integrity ... will be defended at all cost and no external force is allowed to conduct operations ... inside Pakistan . '' His announcement came amid media reports that several months ago , President Bush authorized U.S. special forces to carry out ground assaults inside Pakistan without first seeking Islamabad 's permission . Meanwhile , a suicide attack late Tuesday evening in the restive area of Swat killed three soldiers and wounded six others , the Pakistani military told CNN . Pakistan army spokesman Major Murad Khan said the driver of the suicide car bomb tried to ram the gate of a military checkpoint at a school in the Swat District . Troops shot from the check-post before the attacker reached his target , Khan said . The car exploded , and militants shot back as they ran away . The incident happened at a time when Muslims break their fasts in the month of Ramadhan . Swat militants loyal to banned religious leader Maulana Fazlullah have claimed responsibility for the attack , according to the military . The suicide attacker in the car was killed . A few others were also believed to have been killed or injured , but Khan said there were no confirmed numbers because it was dark and the militants removed the bodies of their dead and wounded . The explosion occurred at the Tutano Bandai school of Tehsil Kabal in Swat District in the North West Frontier Province . A military spokesman offer no additional details . CNN 's Jamie McIntyre and Zein Basravi contributed to this report .
Adm. Michael Mullen to meet with Pakistan 's new prime minister and military chief . Relations between U.S. and Pakistan tense since U.S. raid in Pakistani tribal region . Suicide attack kills 3 soldiers , wounds 6 others in Pakistan region of Swat .