Officials in Pakistan say missiles fired by Americans killed 21 Islamist militants in northwest Pakistan Wednesday, most of them members of a powerful insurgent network fighting the U.S. presence in Afghanistan.
But the United States missile strike program in Pakistan is a source of tension between the two countries. Pakistan has protested the strikes, saying they fuel militancy in the country. Meantime, there's been a huge upsurge in violence in the Pakistani city of Karachi in recent weeks. Hundreds of people have been killed in tensions between different ethnic groups. It's often brought the city, of some 18 million people, to a standstill.
Over the last six months, ties between the two nations have grown increasingly strained, complicating U.S. goals for withdrawing from Afghanistan.
- Aleem Maqbool, BBC reporter in Karachi, Pakistan
This segment aired on August 10, 2011.