WASHINGTON — A Pentagon program that delegated management of a huge swath of the internet to a Florida company in January — just minutes before President Donald Trump left office — has ended as mysteriously as it began, with the Defense Department this week retaking control of 175 million IP addresses. The program had drawn scrutiny because of its unusual timing, starting amid a politically charged changeover of federal power, and because of its enormous scale. At its peak, the company, Global Resource Systems, controlled almost 6% of a section of the internet called IPv4. The IP addresses had been...