The two attacks by drone aircraft took place in South Waziristan, a Mehsud stronghold close to the Afghan border where Pakistani troops are gearing up for a military offensive, two officials said on condition of anonymity because they were not authorized to speak to the media.They took place as U.S. Homeland Security Secretary Janet Napolitano met government officials in the Pakistani capital, Islamabad. She discussed topics of "mutual interest" with them, a U.S. Embassy spokesman said.The drone attacks were the latest in a string of more than 40 believed to have been be carried out by the United States against militant targets in the border area since last August. Washington does not directly acknowledge being responsible for the attacks, which kill civilians as well as militants.Most Pakistanis criticize the drone attacks, and Islamabad officially protests them as violations of its sovereignty. Still, most experts believe the government secretly approves of them and likely provides the United States with intelligence.In one attack Friday, two missiles struck an abandoned seminary in the village of Mantoi that was being used by militants from Mehsud's group for training, the officials said. In the other strike, one missile hit an insurgent communications center in the nearby village of Kokat Khel, they said.In total, 17 people were killed and 27 others were wounded, they said.However, Maulvi Noor Syed, an aide to Mehsud, told The Associated Press that three Taliban fighters died in the strikes."We lost only three mujahedeen (holy warriors) in today's American missile attack," Syed said. "These attacks cannot cause any damage to us."Access to the rugged, dangerous region is strictly controlled, and the death toll could not be independently verified.The drone attack came as U.S. Marines in neighboring Afghanistan pushed deeper in the southern Helmand province, a day after 4,000 Marines launched a major anti-Taliban offensive. Pakistan said it moved troops to the stretch of its border opposite Helmand to stop militants fleeing the American assault.The United States wants Pakistan to crack down on militants on its side of the border, believing it essential to stabilizing Afghanistan eight years after the invasion that ousted the Taliban there.The Pakistani military launched an offensive in the Swat region close to the border in early May and is currently gearing up for operations in South Waziristan to eliminate Mehsud, who has been blamed for a string of deadly suicide attacks across the country that have killed more than 100 people in the past month.In neighboring North Waziristan on Friday, Pakistani warplanes bombed suspected militant hide-outs, killing at least four insurgents and wounding seven others, two more intelligence officials said. Those airstrikes hit targets where Taliban fighters killed 16 government troops in an ambush earlier this week, the officials said, also speaking on condition of anonymity because they were not authorized to speak to the media.The U.S. appears to be ramping up the pressure on Mehsud, who is viewed in Islamabad with growing alarm. Last week, the Taliban leader narrowly escaped a strike on a funeral for militants killed in an earlier drone attack. Eighty people died in the strike, although Mehsud escaped unharmed.