ISLAMABAD, Pakistan — It was a signal moment in Pakistan’s political development: A huge demonstration forced the restoration of a dismissed chief justice, Iftikhar Muhammad Chaudhry, a symbol of democracy and the rule of law. The army did not stage a coup, but insisted that the government accept a compromise.

The deal between President Asif Ali Zardari and Nawaz Sharif, the leader of the main opposition party, does not herald a solution to the instability of this nuclear-armed nation. Nor does it ensure the Obama administration’s primary objective of tamping down the powerful Islamic insurgency that threatens both Pakistan and Afghanistan.

How the two Pakistani politicians will resolve their rivalry is but one of many uncertainties. Another is whether the domestic political struggle will allow them — or the military — to focus on their country’s deteriorating security situation.

President Zardari has been severely weakened by his efforts to squelch a national protest and faces defections from the usually cohesive Pakistan Peoples Party. His opponent, Mr. Sharif, emerged as a leader in waiting, but with no clear path to power.