Pakistani troops have cleared Taliban fighters from most towns in a district close to the border with Afghanistan, the army has said.
Major General Athar Abbas, the army spokesman, told reporters in Sararogha in South Waziristan on Tuesday that the "major town and population centres have been secured".
Pakistan deployed 30,000 troops to South Waziristan a month ago, vowing to crush the Tehreek-e-Taliban network which has been blamed for scores of deadly bomb attacks across the country.
At least 550 Taliban fighters and 70 Pakistani soldiers have been killed since October 17, Abbas said.
"The myth has been broken that this was a graveyard for empires and it would be a graveyard for the army," he said.
However, Abbas cautioned that many of the Taliban leaders had melted away as the military had advanced into the region.
"We still believe many are still here. They have gone to the countryside, the forested areas, to villages and into the caves," he said.
"After taking complete control of the roads and the tracks, we are going to chase them in the forested areas, wherever they are hiding in the countryside."
Sararogha itself, which before the fighting was home to 10,000 people, was deserted and its mudbrick homes destroyed when journalists visited on Tuesday.
"The military is trying to take over the populated centres, but the population has of course left," Al Jazeera's Kamal Hyder, reporting from Sararogha, said.
"Their first priority is to gain a foothold in South Waziristan before their troops start fanning out into the hinterland."
Thousands of people fled South Waziristan as the military offensive got under way, but despite the apparent security improvements they will find the area devastated on their return.
Brigadier Mohammad Shafiq said that his men had battled hard to recapture a base that had previously been seized by Taliban fighters.
"Their defences were well-constructed and we faced extremely tough resistance," he said.
Soldiers showed journalists purported Taliban pamphlets, including one on making bombs, captured ammunition and weapons, and pouched vests that suicide bombers pack with explosives.
'Capture or kill'
In nearby Ladha, Brigadier Farrukh Jamal said his men had surrounded 35 Taliban fighters hiding in the forest-covered mountains.
"They are hiding in caves and we will capture them soon or kill them," he said.
Several rifle shots rang out and smoke rose over the slopes where the Taliban were said to be hiding.
The claims of success came after James Jones, the US national security adviser reportedly delivered a letter from Barack Obama, the US president, Asif Ali Zardari, his Pakistani counterpart, urging him to engage in a campaign against fighters threatening Afghanistan as well as Pakistan.
The New York Times newspaper said that in the letter Obama presented a range of fresh incentives to Islamabad, including enhanced intelligence sharing and military co-operation.
There has been an increase in suicide bombings since the military offensive was launched, with Peshawar, the main city in the North West Frontier Province, the scene of a previous ofensive against Taliban fighters, bearing the brunt of many attacks.
Source: Al Jazeera and agencies