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Questions swirled about whether Prime Minister Nawaz Sharif would abandon government-sponsored peace talks with the Pakistani Taliban in favor of a military offensive. The Pakistani air forces responded to the recent violence by launching airstrikes on militants in the nation’s northwestern tribal region.

U.S. forces have never occupied Pakistan, but the Obama administration for years pursued a campaign of drone strikes against suspected al Qaeda leaders in the tribal region on the Pakistani side of the border with Afghanistan.

Reza Jan, an analyst focused on Pakistan at the American Enterprise Institute, said the administration appeared to halt U.S. drone strikes in the region six months ago, although it remains unclear whether the decline in such strikes could be directly related to the Pakistani Taliban’s capability of launching attacks like the ones that struck Karachi this week.

“What is likely is that neither the Taliban in Pakistan, nor al Qaeda have been molested by drone strikes in the past six months, and we’ve seen that the Taliban in Pakistan shows remarkable resiliency to these drone attacks,” Mr. Reza said. “They’ll get hit, they might lose an important leader, but a few months later they’ve got somebody else in the role and their attack stream is unaffected.”

In addition to Mr. McCain, other Republicans on Capitol Hill questioned whether the Obama administration is moving to hastily in pulling U.S. forces from Afghanistan.

“I want to make sure at the end of the day that we’re not just rushing to fulfill a campaign promise” to withdraw U.S. troops, said Rep. Adam Kinzinger, Illinois Republican and an Air Force major who served in Iraq and Afghanistan.

“In 20 years, history books will judge us very harshly, if that’s the case,” Mr. Kinzinger said during a hearing Tuesday focused on future U.S. spending in Afghanistan.

S.A. Miller and Philip Swartz contributed to this article, which is based in part on wire service reports.