Stepping up its involvement in Mexico’s drug war, the Obama administration has begun sending drones deep into Mexican territory to gather intelligence that helps locate major traffickers and follow their networks, according to American and Mexican officials.

The CIA is using new, smaller missiles and advanced surveillance techniques to minimize civilian casualties in its targeted killings of suspected insurgents in Pakistan's tribal areas, according to current and former officials in the United States and Pakistan.

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 U.S. military official said on Monday.