Pakistani warplanes have bombed suspected militant hideouts in the volatile South Waziristan region.
Pakistani officials say the jets attacked a number of locations in the tribal area Friday -- all considered strongholds of Pakistani Taliban leader Baitullah Mehsud.
Officials also say Pakistani ground forces have started to enter Mehsud's territory, exchanging fire with Taliban militants. The officials say it is not clear how many militants were killed.
The latest Pakistani offensive comes as the United Nations World Food Program warns the Pakistani Taliban are increasingly targeting international aid agencies.
World Food Program spokesman Paul Risely says the bombing of the Pearl Continental Hotel in the northwestern city of Peshawar earlier this month, which killed nine people, was intended as a message to aid groups.
An estimated 2.5 million people already have fled fighting in Pakistan's northwest since the military began battling Taliban fighters in the greater Swat valley more than a month ago. Reports from South Waziristan say some residents have fled their homes in anticipation of violence.
Pakistani Taliban leader Baitullah Mehsud is one of the most wanted militants in Pakistan for scores of attacks against government and civilian targets. He is also believed to be a key facilitator for al-Qaida fighters in the country.
Caroline Wadhams, a senior policy analyst with the Center for American Progress in Washington, tells VOA Deewa Radio the U.S. government is feeling more optimistic about Pakistan's efforts to take on militants. But she also says the Pakistani military is still not doing enough to prevent militant attacks on sites in neighboring Afghanistan.
Also Friday, Pakistani officials blamed Taliban militants for bombing three schools in the Bajaur area but said no one had been hurt.
Officials said a separate bombing at a bus stop in Dera Murad Jamali, in southwestern Pakistan, killed at least 12 people.
Officials also raised the death toll from a suspected U.S. missile strike Thursday from nine to 13. The strike targeted an area west of Wana, a major town near the Afghan border in Pakistan's South Waziristan region.