The head of a powerful House panel is threatening to withhold defense funding over the department's alleged stonewalling in a probe of the controversial swap of five Taliban leaders for Sgt. Bowe Bergdahl. Former Defense Secretary Chuck Hagel had initially pledged to respond to questions, when lawmakers first demanded to know why the Pentagon had not given Congress the requisite 30-day notice before proceeding with the May 31 prisoner trade. But nearly a year later, the Pentagon has released only a trickle of highly redacted emails from before the swap. Republican lawmakers now plan to attempt the unusual step of...