Messages posted recently by prominent contributors to Islamist Web sites are seeking specific information on U.S. military targets in hopes of carrying out an attack on Navy ships in the Persian Gulf, according to a U.S.-based group that tracks such sites. One post on the jihadi forum Al-Falluja calls for information such as the “name of the particular naval unit to be targeted, its exact location, the number of troops on board the warship and their ranks, familial status, where their families live, the type of weapons the warship carries … and the number of nuclear bombs onboard,” reads a...