WASHINGTON — For many Americans, today marks the fifth anniversary of the start of an Iraq war that was not worth fighting, one that has cost thousands of lives, and more than half a trillion dollars. For the Bush administration, however, it is the first anniversary of an Iraq strategy that it believes has finally started to succeed.

It has been about a year since General Petraeus arrived to command American forces in Iraq, Ambassador Ryan Crocker took over as the chief American diplomat and the military deployed 30,000 more troops to protect and rebuild neighborhoods.

Officials now running the American effort express frustration that the gains wrought by their new security, political, and economic policies — in particular, sharply reduced violence — are continually weighed against the first four years of the war, when Iraq unraveled in insurgency and sectarian strife.

“I came to Washington to describe what we’re doing,” Mr. Crocker’s senior deputy in charge of reconstruction and the Iraqi economy, Charles Ries, said during a visit last week. “At almost every meeting, somebody wants me to describe what we used to do. … I know why people raise these questions, but I don’t feel it’s something I can speak to. The times were different then.”

Today’s policy is fundamentally different from the impatient mind-set of 2003, in both lowered American expectations and a less imperious approach to dealing with Iraqi authorities. “In those days,” Mr. Ries said, “we decided what (the Iraqis) needed, and we built it.” Today, he said, Iraqis are asked what they want, and then told that while America will help, they will have to pay for most of it themselves.

Yet as the administration now requests additional war funding and calls for a pause in promised troop withdrawals, some question its right to a second chance. “Like a tourniquet,” the troop increase “has stopped the bleeding,” Senator Reed, a Democrat from Rhode Island, a former Army Ranger and senior member of the Armed Services Committee, reported last week after his 11th trip to Iraq. What he has not seen, Mr. Reed said, are the surgery and recovery that would begin to heal the wound that Iraq has become. And even American officials acknowledge that the troop increase has not led to the political reconciliation the administration had hoped for.

Others see the past year’s successes as fragile and reversible, and less consequential than the pain that preceded them. “I think they have it righter than they ever have before,” an Iraq expert with the U.S. Institute of Peace, Daniel Serwer, said of the administration. “But the fact is that those four other years did exist, and they condition a lot of what can and cannot happen now. There’s a history here, there’s a lot of blood and guts on the floor, literally.”