WASHINGTON -- When Matthew Hoh joined the Foreign Service early this year, he was exactly the kind of smart civil-military hybrid the administration was looking for to help expand its development efforts in Afghanistan.

A former Marine Corps captain with combat experience in Iraq, Mr. Hoh had also served in uniform at the Pentagon, and as a civilian in Iraq and at the State Department. By July, he was the senior U.S. civilian in Zabul province, a Taliban hotbed.

But last month, in a move that has sent ripples all the way to the White House, Mr. Hoh, 36, became the first U.S. official known to resign in protest over the Afghan war, which he had come to believe simply fueled the insurgency.

"I have lost understanding of and confidence in the strategic purposes of the United States' presence in Afghanistan," he wrote Sept. 10 in a four-page letter to the department's head of personnel. "I have doubts and reservations about our current strategy and planned future strategy, but my resignation is based not upon how we are pursuing this war, but why and to what end."

The reaction to Mr. Hoh's letter was immediate. Senior U.S. officials, concerned that they would lose an outstanding officer and perhaps gain a prominent critic, appealed to him to stay.

U.S. Ambassador Karl Eikenberry brought him to Kabul and offered him a job on his senior embassy staff. Mr. Hoh declined.

From there, he was flown home for a face-to-face meeting with Richard Holbrooke, the administration's special representative for Afghanistan and Pakistan. "We took his letter very seriously, because he was a good officer," Mr. Holbrooke said in an interview. "We all thought that given how serious his letter was, how much commitment there was and his prior track record, we should pay close attention to him."

While he did not share Mr. Hoh's view that the war "wasn't worth the fight," Mr. Holbrooke said, "I agreed with much of his analysis." He asked Mr. Hoh to join his team in Washington, saying that "if he really wanted to affect policy and help reduce the cost of the war on lives and treasure," why not be "inside the building, rather than outside, where you can get a lot of attention but you won't have the same political impact?"

Mr. Hoh accepted the argument and the job, but changed his mind a week later. "I recognize the career implications, but it wasn't the right thing to do," he said in an interview.

"There are plenty of dudes who need to be killed," Mr. Hoh said of al-Qaida and the Taliban. "I was never more happy than when our Iraq team whacked a bunch of guys."

But many Afghans, he wrote in his resignation letter, are fighting the United States largely because its troops are there -- a growing military presence in villages and valleys where outsiders, including other Afghans, are not welcome and where the corrupt, U.S.-backed national government is rejected.

While the Taliban is a malign presence, and Pakistan-based al-Qaida needs to be confronted, he said, the United States is asking its troops to die in Afghanistan for what is essentially a far-off civil war.

As the White House deliberates over whether to deploy more troops, Mr. Hoh said he decided to speak out publicly because "I want people in Iowa, people in Arkansas, people in Arizona, to call their congressman and say 'Listen, I don't think this is right.'

Mr. Hoh's journey -- from Marine, reconstruction expert and diplomat, to war protester -- was not an easy one. Over the weeks he spent thinking about and drafting his resignation letter, he said, "I felt physically nauseous at times."

After graduation from Tufts University and a desk job at a publishing firm, he joined the Marines in 1998. After five years in Japan and at the Pentagon, at a point early in the Iraq war when it appeared to many in the military that the conflict was all but over, he left the Marines to join the private sector, only to be recruited as a Defense Department civilian in Iraq. A trained combat engineer, he was sent to manage reconstruction in Tikrit, Saddam Hussein's home town.

"At one point," Mr. Hoh said, "I employed up to 5,000 Iraqis," handing out tens of millions of dollars to construct roads and mosques. His program was one of the few later praised as a success by the U.S. special inspector general for Iraq reconstruction.

In 2005, Mr. Hoh took a job with BearingPoint, a major technology and management contractor at the State Department, and was sent to its Iraq desk.

When the U.S. effort in Iraq began to go badly in early 2006, he was recalled to active duty from the Reserves. He assumed command of a company in Anbar province, where Marines were dying by the dozens.

Mr. Hoh came home in the spring of 2007 with citations for what one Marine evaluator called "uncommon bravery," a recommendation for promotion and what he later recognized was post -traumatic stress disorder. Like many Marines in similar situations, he didn't seek help. "The only thing I did," he said, "was drink myself blind."

Eventually, Mr. Hoh began talking to friends and researching the subject online. "It's something I'll carry for the rest of my life," he said of his Iraq experiences. "But it's something I've settled, I've reconciled with."

Late last year, a friend told Mr. Hoh that the State Department was offering year-long renewable hires for Foreign Service officers in Afghanistan. It was a chance, he thought, to use his Tikrit development skills under a fresh administration that promised a new strategy.

In photographs he brought home from Afghanistan, Mr. Hoh appears with a neatly trimmed beard and a pristine flak jacket. He stands with Mr. Eikenberry, the ambassador, on visits to northern Kunar province and Zabul, in the south. He walks with Zabul Gov. Mohammed Ashraf Naseri, confers with U.S. military officers and sits at food-laden meeting tables with Afghan tribal leaders.

He arrived in Zabul after two months in a civilian staff job at the military brigade headquarters in Jalalabad, in eastern Afghanistan.

It was in Jalalabad that his doubts started to form. Mr. Hoh was assigned to research the response to a question Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, asked during an April visit. He wanted to know why the U.S. military had been operating for years in the Korengal Valley, an isolated spot near Afghanistan's eastern border with Pakistan, where a number of American had been killed.

Mr. Hoh concluded that there was no good reason. The people of Korengal didn't want them; the insurgency appeared to have arrived in strength only after the Americans did, and the battle between the two forces had achieved only a bloody stalemate.

Korengal and other areas, he said, taught him "how localized the insurgency was. I didn't realize that a group in this valley here has no connection with an insurgent group two kilometers away." Hundreds, maybe thousands, of groups across Afghanistan, he decided, had few ideological ties to the Taliban, but took its money to fight the foreign intruders and maintain their own power bases.

"That's really what kind of shook me," he said. "I thought it was more nationalistic. But it's localism. I would call it valley-ism."

In accord with administration policy of decentralizing power in Afghanistan, Mr. Hoh worked to increase the political capabilities of Mr. Naseri, the provincial governor, and other local officials. "Materially, I don't think we accomplished much," he said in retrospect, but "I think I did represent our government well."

Mr. Hoh's doubts increased with Afghanistan's Aug. 20 presidential election, marked by low turnout and widespread fraud. He concluded, he said in his resignation letter, that the war "has violently and savagely pitted the urban, secular, educated and modern of Afghanistan against the rural, religious, illiterate and traditional. It is this latter group that composes and supports the Pashtun insurgency."

With "multiple, seemingly infinite, local groups," he wrote, the insurgency "is fed by what is perceived by the Pashtun people as a continued and sustained assault, going back centuries, on Pashtun land, culture, traditions and religion by internal and external enemies. The U.S. and NATO presence in Pashtun valleys and villages, as well as Afghan army and police units that are led and composed of non-Pashtun soldiers and police, provide an occupation force against which the insurgency is justified."

American families, he said at the end of the letter, "must be reassured their dead have sacrificed for a purpose worthy of futures lost, love vanished, and promised dreams unkept. I have lost confidence such assurances can be made any more."

This week, Mr. Hoh is to meet with Vice President Joseph R. Biden's foreign policy adviser, Antony Blinken, at Mr. Blinken's invitation. If the United States is to remain in Afghanistan, Mr. Hoh said, he will advise a reduction in combat forces.

He also will recommend providing more support for Pakistan, better U.S. communication and propaganda skills to match those of al-Qaida and more pressure on Afghan President Hamid Karzai to clean up government corruption -- all options being discussed in White House deliberations.

"We want to have some kind of governance there, and we have some obligation for it not to be a bloodbath," Mr. Hoh said. "But you have to draw the line somewhere, and say this is their problem to solve."

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