Pakistani helicopter gunships attacked Taliban bases near the Afghan border on Wednesday as the army urged NATO forces to seal the frontier to stem cross-border movement of militants. Pakistani forces launched an offensive to wrest control of the lawless South Waziristan region on Saturday after militants rocked the country with a string of bomb and suicide attacks in recent weeks. As government forces pressed ahead with the Waziristan offensive, Pakistan military called on the NATO troops in Afghanistan to seal the border "to prevent cross-border movement and flow of weapons."