New Delhi, Feb. 27 -- Tensions between Pakistan and Afghanistan have escalated sharply following cross-border airstrikes and military exchanges along the Durand Line. Pakistan bombed major cities in Afghanistan, including the capital, Kabul, on Friday, with Islamabad's defence minister declaring the neighbours at open war after months of tit-for-tat clashes. The declaration came hours after Afghan forces attacked Pakistani border troops in what the Taliban government described as retaliation for earlier deadly airstrikes.The Afghan Ministry of Defence said eight Afghan soldiers were killed in the border clash, and several civilians were injured near the Torkham crossing at a camp for returnees from Pakistan. The Taliban government confirm...