When Larry Diamond left for Baghdad in January as an adviser to the U.S. occupation authority, he took all the equipment he believed he needed to help construct a hopeful new nation out of the ashes of dictatorship: the academic models he had crafted over the years as an authority on building democracies, and confidence those models would work.

But the jarring reality of Iraq, with its escalating violence and collapsing civic order, forced Diamond to look for a few new tools beyond those listed in the textbooks. When he speaks now of the models for building democratic countries, he stresses a different set of equipment, which he found in short supply: body armor, armor-plated cars, a huge military presence.

The story of Iraq, this onetime optimist believes, is a tale of missed opportunities.

"We just bungled this so badly," said Diamond, a 52-year-old senior fellow at Stanford University's Hoover Institution. "We just weren't honest with ourselves or with the American people about what was going to be needed to secure the country."

Diamond was a senior adviser to the Coalition Provisional Authority and spent several initially hopeful months in Iraq -- lecturing on democracy, even in mosques, encouraging people to participate and helping shape laws that embodied his vision. He returned to Palo Alto in early April for a short break, then ran into an emotional brick wall, he said, when he contemplated the mess he had left behind.

Last Thursday, when it came time for Diamond to return, he did not get on the plane.

Instead, he was in his office at the Hoover Tower, disillusioned over the desperate turn of events he had witnessed and what he feels was a country allowed to spin out of control, in large part, he says, because of the Bush administration's unwillingness to commit a big enough force to protect Iraqis from militias and insurgents.

"You can't develop democracy without security," he said. "In Iraq, it's really a security nightmare that did not have to be. If you don't get that right, nothing else is possible. Everything else is connected to that."

Few people would seem better prepared for the job in Iraq than Diamond. He is coordinator of the Democracy Program at Stanford's Center for Democracy, Development and the Rule of Law, and he has been co-editor since 1990 of the Journal of Democracy. He has done extensive fieldwork in Taiwan and Nigeria.

He said he had initially opposed the war in Iraq because he felt the United States needed broader international support before attacking, but after the main ground fighting ended last April, he was ready to help.

"Once the war was over, I felt we had a moral and political obligation to the Iraqis to try and help build something better," he said. "That was clear in my mind. I didn't agonize over that. I really had something to contribute."

So late last year, after the Bush administration and the provisional authority outlined their plans for writing an interim constitution and handing over sovereignty on June 30, Diamond said he began to speak with officials about playing a role and implementing some of the ideas he had spent his career developing.

Arriving in Baghdad in early January, he said, he was sober-minded about the challenges but encouraged by much of what he found.

"When I got there on the ground, I was actually hopeful as I met some of the young people, women, civic groups, and their eagerness for change," he said.

"It was mind-blowing, really,'' he added. "There were people who wanted to know how to make democracy work. There were so many positive signs. Civil society was very weak, as you'd expect, but it was beginning to reconstitute itself. There was a lot of energy, a lot of passion, a lot of creativity and a lot of desire to learn. I even had a good experience with some mullahs who supported us."

Diamond said that he had some successes. He said he sought to provide female representatives a guaranteed number of seats in the provisional parliament and helped secure for them a 25 percent stake.

He helped strengthen some of the provisions in the interim constitution supporting the development of civic groups to organize people at a grassroots level, and worked to make the new government structure somewhat decentralized as a way of giving minority groups more of a voice and providing opportunities for grassroots participation. And he instructed, while learning.

In January, he outlined the four basic principles of democracy in a speech at Hilla University, discussing such issues as checks and balances and the rule of law. In February, at a conference in Baghdad on decentralization, he presented a 12-point description of how civil society helps build a stronger democracy.

In another address to Iraqis in late March, Diamond called the transitional law, as the interim constitution is called, the right path to "a true democracy," praised the spirit of compromise he found and promised the Iraqis that their nascent democracy would lead the Arab world.

But Diamond said it was around that time that the insurgency grew bolder, that more Americans and Iraqis began to die and that security appeared to be collapsing. He said he shuddered as he began to see other advisers getting killed on the same roads he traveled.

And then he had what he describes as a painful, transforming experience.

"I had one of those moments when you cut through all the bull," he said. "I was speaking to this women's group, and one woman got up and asked, 'If we do all these things, who's going to protect us?' " Diamond recalled. "That was the moment when I said to myself, 'Oh my God, some of these women are going to be assassinated because they are here listening to me.' It just struck me between the eyes."

As the violence spread, Diamond said, he felt ever more painfully the mistake the United States had made by not sending in more troops to keep the insurgents at bay.

The American policies basically encouraged Iraqis to stand up -- only to face the threat of being mowed down for doing so, he said.

"It was totally hypocritical of us to do one and not the other," Diamond said of the lack of security.

As a result, he said, democratization suffered potentially fatal setbacks. He was angry, he added, not just because optimistic Iraqis were being killed, but because the downward spiral was preventable.

His recommendations for rescuing the situation run counter to some of the policies that the Bush administration insists it will not alter. Diamond said that, in his view, the United States must more than double its current military force of about 135,000 and confront the violent Iraqi militias consistently, while offering political benefits to those who lay down their arms and accept democratic institutions.

The best he can say about the prospects in Iraq now is that, as he puts it, "civil war is not inevitable."

Diamond said that, realistically, he never expected a flawless democracy to emerge in just months. It was more likely, he said, that the legacies of traditional Arab society and dictatorship would have produced some rigged elections, corruption and sporadic violence. But with greater security, there would have been, at the least, a constitution and a more flexible and responsive government.

None of that is likely to happen now, he said, without significantly more American troops and a more assertive military stance.

"The literature stresses the overwhelming need to get the security under control," Diamond said. "Nothing that happened could not have been anticipated. I don't think we were applying the lessons of the past as systematically as they should have been, to put it as politely as possible."