As the Iraq war passes its fifth anniversary this week, the U.S. military is bracing for a transition that will reduce its combat power in Iraq by more than 20 percent by July, as the surge forces President Bush deployed last year end their tours of duty. The question for officials, military officers and analysts is whether the security gains the surge brought can be sustained with fewer U.S. troops in Iraq in the coming months, and perhaps even fewer as the year goes on. VOA's Al Pessin reports from the Pentagon.

In January of last year the situation in Iraq was spiraling out of control. The main subject of debate was whether the country was in a civil war, or only verging on civil war. A growing number of experts and members of Congress were calling for a U.S. withdrawal. But President Bush went the other way.

"I've committed more than 20,000 additional American troops to Iraq," he said. "The vast majority of them - five brigades - will be deployed to Baghdad."

It was a huge gamble, in both military and political terms. And it was accompanied by a change in tactics to a new, untested counterinsurgency strategy.

Now, more than a year later, the surge is ending with the lowest level of violence in years, the lowest U.S. casualty rates in years, progress on Iraqi political issues that had been stalled for years and more involvement by Iraqi security forces than at any time since the fall of Saddam Hussein.

Longtime skeptic of Bush administration Iraq policy Anthony Cordesman of the Center for Strategic and International Studies visited Iraq last month and found progress has been made. But he says it has been a long time coming.

"We have certainly learned a great deal about nation building, although we're scarcely well prepared for it," he said. "We understand the consequences of many of our early mistakes. And we have a far more sophisticated force to fight counterinsurgency than we did when we began. But it has taken us half a decade to get to the position where we really are ready to fight this kind of war."

Analysts say those 'early mistakes' include not having enough coalition troops to guarantee security and disbanding the Iraqi military, which further reduced the number of security forces and also provided men and weapons for the insurgency. Cordesman says it has been a long road back for the Iraqi security forces.

"When you go to Iraq you discover goals we set for 2007 probably won't be met until 2009 in force quality," he said. "That still is remarkable progress for creating a force from so low a base."

But Cordesman and other analysts note that the security improvements during the last year did not come only from the U.S. surge and improvements in the Iraqi security forces. They note that the leader of the main Shi'ite militia declared a ceasefire and the main Sunni insurgent group, al-Qaida in Iraq, alienated many Iraqis with its extreme Islamist views and its indiscriminate violence.

One result was a shift by Sunni tribes in western Iraq from support for the insurgents to support for the government and the coalition, and similar moves by other tribes and local groups across the country. More than 90,000 Iraqis have joined local security forces working with the Iraqi police.

Analysts have been saying for months that Iraqi leaders must do more to take advantage of the improved security and build long-term stability. Among them is another recent visitor to Iraq, Michele Flournoy of the Center for a New American Security.

"The most disturbing thing that I observed while there is that I really didn't sense any sense of urgency on the part of the central government stepping into this breach, trying to take advantage of the security situation," she said. "The second most disturbing thing I saw was that I didn't feel that there was a clear political strategy on our part, on the part of the U.S., to push the Iraqis to take advantage of this opportunity."

Flournoy says the coming months are a key period for political progress in Iraq on such pending issues as revenue sharing between the central government and the provinces and planning for local elections. U.S. officials say there has been what they call "bottom up" reconciliation, rather than the "top down" type of legislated reconciliation they had originally wanted. Now, experts say, the parliament must follow through on what individuals, tribes and provinces have done. If that happens, Flournoy says, military commanders tell her the end of the surge should not affect the security situation, and further drawdowns of U.S. and coalition forces could be possible.

"The next president could inherit a situation that would allow a substantial drawdown without having Iraq backslide into civil war," she said. "But that means that we have to play our cards very prudently and very well between now and then, and I'm not reassured that we're doing that."

By the sixth anniversary of the U.S.-led invasion of Iraq, there will be a new government in Washington. Analysts and officials say whether that government will be able to continue to reduce the U.S. military role in Iraq without causing instability there will very much depend on whether the Bush administration, in its final months, can continue to build the Iraqi security forces and can successfully push the Iraqi government toward the kind of broad reconciliation that has so far been lacking in spite of the security gains.