Around the clock, about 16 times a day, drones take off or land at a U.S. military base [in Djibouti], the combat hub for the Obama administration's ... wars in the Horn of Africa and the Middle East. Some of the unmanned aircraft are bound for Somalia. Most of the armed drones, however, veer north across the Gulf of Aden to Yemen. Camp Lemonnier began as a temporary staging ground for U.S. Marines looking for a foothold in the region a decade ago. Over the past two years, the U.S. military has clandestinely transformed it into the busiest Predator drone base outside the Afghan war zone. The Obama administration has gone to extraordinary lengths to conceal the legal and operational details of its targeted-killing program. Increasingly, the orders to find, track or kill [targeted] people are delivered to Camp Lemonnier. Secrecy blankets most of the [500-acre] camp's activities. In August, the Defense Department delivered a master plan to Congress detailing how the camp will be used over the next quarter-century. About $1.4 billion in construction projects are on the drawing board, including a huge new compound that could house up to 1,100 Special Operations forces, more than triple the current number. Drones will continue to be in the forefront. Today, Camp Lemonnier is the centerpiece of an expanding constellation of half a dozen U.S. drone and surveillance bases in Africa ... from Mali to Libya to the Central African Republic. The U.S. military also flies drones from small civilian airports in Ethiopia and the Seychelles, but those operations pale in comparison to what is unfolding in Djibouti.