The Pentagon aims to deliver a fleet of surveillance drones to Pakistan within a year, but weaponized versions of the unmanned aircraft are still off-limits, a US military official said on Monday. US Defense Secretary Robert Gates announced plans in January to provide Islamabad with what aides said at the time were 12 Shadow drones, aiming to boost its ability to track insurgents, reports Reuters. But a senior US military official, briefing reporters at the Pentagon on the condition of anonymity, said Islamabad was still weighing whether Shadow drones were the model of unmanned aircraft best suited to its needs. We looked at Shadows. We looked at Scan Eagles and other tactical UAVs that are out and about and what we want to do is try to find out which model is best, the official said, referring to drones as unmanned aerial vehicles, or UAVs.