.Political tension

Political tensions had been escalating in recent days. After joining forces to oust Musharraf in March 2008, Zardari and Sharif quickly parted ways and revived their decades-old poisonous rivalry. Zardari, who claimed the presidency for himself, reneged on a commitment to Sharif to reinstate the deposed Chief Justice Iftikar Chaudhry, who, along with a raft of other judges, was removed by Musharraf when he imposed emergency rule. Last month, in a controversial ruling, the Supreme Court barred Sharif and his younger brother Shahbaz from standing for elected office. The decision triggered the collapse of the Punjab government led by Shahbaz as Zardari moved swiftly to impose governor's rule on the largest and wealthiest province, handing over control to a key ally, Salmaan Taseer. The Sharifs have since been staging political rallies across Punjab, rallying support for the protest march with a series of inflammatory speeches denouncing Zardari's government.
See pictures of Pakistan's vulnerable North-West Frontier Province.
See TIME's Pictures of the Week.