Islamabad ? Pakistani troops backed by attack helicopters stepped up an operation to push the Taliban farther away from the capital Friday, saying they killed at least 55 fighters. But the government was resisting Western pressure to expand the crackdown and abandon peace talks with militants who want to impose their brand of Islam across this nuclear-armed country.

The army launched the drive to retake Buner, a poor, hilly region just 60 miles from Islamabad, on Tuesday after Taliban from the neighboring Swat Valley overran it under cover of a controversial peace pact.

The Obama administration has welcomed the assault. It views the Swat deal, which calls for the imposition of Islamic law in the surrounding area of northwest Pakistan bordering Afghanistan, as a surrender to allies of al-Qaida. And it has expressed growing doubts about Pakistan’s stability as the Taliban have edged closer to Islamabad.