“As a child studying in a madrasa in Afghanistan, Mohammad Khalid Tahir dreamed of waging jihad. By the time he was a teenager, he had joined the Taliban and celebrated when they seized power from the U.S.-backed government two years ago. But the high from that victory did not last. Reassigned as a soldier in the capital, he frequently complained that he was bored and longed to return to his life’s purpose, according to his family. So this spring, he did — but across the border in Pakistan. “Our only expectation is to be martyred,” Mr. Tahir says in a video of him en route to Pakistan that was viewed by The New York Times. About a month later, he was killed by Pakistani security forces, his relatives said. As a generation of fighters raised in war now finds itself stuck in a country at peace, hundreds of young Taliban soldiers have crossed illegally into Pakistan to battle alongside an insurgent group, according to Taliban members, local leaders and security analysts.”