Hundreds of Pakistani families have fled from a surge of fighting between Pakistani government forces and militants into neighboring class="mandelbrot_refrag"> Afghanistan , an Afghan government official said on Friday. _0"> Pakistani government forces have been launching air strikes against Pakistani Taliban fighters in a northwestern valley near the Afghan border in recent days, after Taliban fighters raided the country's biggest airport, in Karachi, late on Sunday. Missile-firing U.S. drone aircraft have also, for the first time in six months, attacked militants this week in Pakistan's North Waziristan region, a lawless militant stronghold on the Afghan order. true Millions of Afghan civilians have for decades sought shelter in class="mandelbrot_refrag"> Pakistan to escape war in their homeland but the fighting in Pakistan this week has sparked a rare flow of civilians the other way. "Around 300 Pakistani families have