"While we favor shipping cargo via Pakistan because of (lower) cost, we have built flexibility and redundancy into our overall system of air, sea and ground routes to transport cargo into and out of Afghanistan," Wright said.
CIA drone strikes in Pakistan have long been a sensitive subject, with officials regularly criticizing them in public as a violation of the country's sovereignty. The issue is more complicated, however, since the government is known to have supported at least some of the attacks in the past.
Routes through Pakistan have been closed in the past. The Pakistani government blocked the routes for seven months following U.S. airstrikes that accidentally killed two dozen soldiers on the Afghan border in November 2011. Pakistan finally reopened the routes after the U.S. apologized.