The CIA received secret permission to attack a wider range of targets, including suspected militants whose names are not known, as part of a dramatic expansion of its campaign of drone strikes in Pakistan's border region. The expanded authority, approved two years ago by the Bush administration and continued by President Obama, permits the agency to rely on what officials describe as pattern of life" analysis ... to target suspected militants, even when their full identities are not known, the officials said. Previously, the CIA was restricted in most cases to killing only individuals whose names were on an approved list. Instead of just a few dozen attacks per year, CIA-operated unmanned aircraft now carry out multiple missile strikes each week against safe houses, training camps and other hiding places used by militants in the tribal belt bordering Afghanistan. "There are a lot of ethical questions here about whether we know who the targets are," said Loch Johnson, an intelligence scholar at the University of Georgia and a former congressional aide. President Bush secretly decided in his last year in office to expand the program. Obama has continued and even streamlined the process, so that CIA Director Leon E. Panetta can sign off on many attacks without notifying the White House beforehand, an official said.