Allied Afghan commanders sent fresh troops on Tuesday to bolster US-led coalition forces battling al-Qaida and Taliban fighters.
Pro-US Afghans returning from the front reported continued firing but less intense than in recent days.
As coalition bombers blasted al-Qaida's mountain strongholds, mine clearers led the way on the ground for allied troops to press on toward Shah-e-Kot, where hundreds of militant soldiers are believed hunkered down.
Hundreds of US-backed Afghan troops ringed the range of eastern Afghanistan's Paktia mountains and their labyrinth of caves to try to block the escape of any renegades.
US aircraft were seen flying over the Gardez area, as part of what the US has called the biggest operation of its anti-terror campaign yet.
On Monday, in the deadliest air and ground offensive of the five-month-old campaign, al-Qaida and Taliban fighters using machine guns and rocket-propelled grenades fired on two US helicopters, killing seven American soldiers.
The helicopters had been taking part in the largest US-led air and ground offensive of the Afghan operation, designed to pound the renegade militants with airstrikes and squeeze them out of their hide-outs.
The offensive - code-named Operation Anaconda after the snake that crushes its prey to death with the muscular coils of its body - marked the first time US conventional ground troops were used in an offensive operation.