The banned group Tehrik-e-Taliban Pakistan, or T.T.P., has intensified attacks on Pakistani security forces, straining ties between Pakistan’s leaders and the Taliban in Afghanistan. Pakistan accuses the Taliban of harboring and supporting T.T.P. fighters, an allegation that the Taliban deny. The Pakistani government is also contending with an increasingly lethal insurgency among Baluch separatists in the country’s southwest. And on the eastern front, Pakistani forces have been placed on alert as India appears to be moving toward military strikes inside the country after a deadly terrorist attack in Kashmir last week. Unlike in past crises, Pakistan no longer enjoys the robust U.S. military support it relied on during the 20-year American presence in Afghanistan. That loss has left the military facing one of its most challenging periods in years. Security officials say they are bracing for a sustained stretch of confronting battle-hardened militants in the west and southwest and the possibility of conventional skirmishes with nuclear-armed India to the east. Abdul Basit, a senior research fellow at the S. Rajaratnam School of International Studies in Singapore, said that the killing of the 54 militants from Afghanistan “paradoxically underscores both a success and a challenge for the Pakistani military,” which he described as “increasingly sandwiched between its eastern and western borders.” “India will keep the threat of potential military action alive,” Mr. Basit said, “and stretch it as far as it can to keep the Pakistan military overstretched.”