A Navy SEAL team targeted a senior leader of the Shabab militant group in a raid on his seaside villa in the Somali town of Baraawe on Saturday, American officials said, in response to a deadly attack on a Nairobi shopping mall for which the group had claimed responsibility. The SEAL team stealthily approached the beachfront house by sea, firing on the unidentified target in a predawn gunbattle that was the most significant raid by American troops on Somali soil since commandos killed Saleh Ali Saleh Nabhan, a Qaeda mastermind, near the same town four years ago. The Shabab leader...