"The N.I.E. update confirmed that the surge strategy the president announced in January of last year is working," a senior Bush senior administration official told The New York Times. "There's more work to be done, but progress has obviously been made."

Officials said that the N.I.E. also found that Iraq is still fragile. Inter-Shiite fighting or the government's failure to approve reconciliation moves that have passed the parliament could derail the process.

The classified document is the sum of information collected by the 16 U.S. intelligence agencies. It is released to members of Congress and senior officials in the executive branch.

U.S. Army Gen. David Petraeus, the coalition commander, is scheduled to be in Washington next week to report to Congress on Iraq.