Mushtaq Ali . Saud Mehsud . Mohammad Yunus Yawar . Reuters Pakistan closed border crossings with Afghanistan on Sunday, Pakistani officials said, following exchanges of fire between the forces of the two countries overnight in which Kabul claimed to have killed 58 Pakistani soldiers. Afghan troops opened fire on Pakistani border posts late on Saturday, with the country's ministry of defence saying this was in retaliation for Pakistani airstrikes in Afghanistan earlier in the week. Pakistan said that it had responded with gun and artillery fire. Afghanistan said it had killed 58 Pakistani soldiers, but gave no details on how it knew of the casualty figures. It also said that 20 Afghan troops were killed or injured. There was no...