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The Pakistani army launched a massive ground offensive in the militant stronghold of South Waziristan Saturday, in an attempt to stem insurgent activity that has claimed scores of lives and threatens to topple Pakistan's government.

More than 30,000 soldiers stormed the region along the Afghan border in the early morning hours. Witnesses reported hearing soldiers exchange gunfire with Taliban militants. Five soldiers and 11 militants were killed.

"We heard sounds of planes and helicopters early Saturday. Then we heard blasts. We are also hearing gunshots and it seems the army is exchanging fire with Taliban," local resident Ajmal Khan told The Associated Press.

Pakistani army spokesperson Maj. Gen. Athar Abbas confirmed early Saturday that an operation was underway to "uproot" the Taliban.

Officials who spoke with AP on condition of anonymity said troops were attacking militants from a number of directions, particularly in towns such as Makeen and Ladha, well-known for their insurgent populations.

The offensive was planned for several months and comes after a series of deadly attacks on government, police and civilian areas that have killed more than 175 people over the past two weeks. This operation is expected to last two months with the hopes of clearing the region of Taliban members.

The United Nations said Saturday that it would help civilians fleeing the region and has been stockpiling supplies nearby. Officials are not expecting a large amount of refugees to flee.

An estimated 150,000 civilians have already fled the area in the last few months after the army made it clear it was planning the assault. An estimated 350,000 people still live there.

CNN reporter Reza Sayah told Â鶹´«Ã½ Channel the ground offensive is a "crucial moment" for the Pakistani military and government, both of which have been unable to stem the tide of militant violence.

"There's been scores of civilians who have been killed during these suicide attacks, and obviously when you have that, there's a lot of pressure on the Pakistani military, on the Pakistani government, to do something," Sayah said Saturday in a telephone interview.

"But the dilemma here in Pakistan over the past few years has been that every time the military has launched any of these offensives, the Pakistani militants simply hide, they melt away in the heavy terrain of the tribal region, they regroup and they hit back with these suicide attacks. And the problem is the Pakistani military hasn't been able to stop this cycle."

While the soldiers engaged in their ground offensive, helicopter gunships and fighter jets pounded a number of locations.

By early Saturday evening, the military announced it had sealed off a number of supply and escape routes.

While the operation will focus on the Pakistani Taliban, which fiercely opposes Pakistan's government, the region is filled with a number of militant groups that officials believe plan attacks against U.S. and NATO troops in nearby Afghanistan.

While soldiers vastly outnumber the 15,000 suspected militants in the region, the terrain is "some of the most severe and mountainous terrain in the world, and these very hardened militants know this severe terrain very well," Sayah said.

The government has tried three times to break into the Taliban stronghold of South Waziristan, but each of those ended with negotiated peace.

However, officials in Pakistan say the recent spate of violence has upped the ante.

"If we fail, everything is rolled back," military spokesperson Gen. Athar Abbas told The Associated Press Friday.

As of Friday, the Pakistani government was awaiting shipments of night-vision goggles from the U.S. to help ground troops cut off insurgent supply routes. Government officials also hoped the U.S. would send Cobra helicopter gunships, laser-guided munitions and intelligence equipment to monitor communications.

The pressure on the Pakistani government to act has increased with the recent spike in suicide attacks.

On Friday, 13 people were killed after a trio of suicide bombers launched an attack on a Peshawar police station in northwest Pakistan.

The attack came only one day after militants launched co-ordinated attacks on three law enforcement outposts in Lahore, Pakistan's second-largest city and cultural centre. A government housing complex in Peshawar was also attacked by a car bomb Thursday, resulting in the death of a small child.

Last week, an attack on the army's headquarters in Rawalpindi killed 23 people.