Soldiers, but not citizens: for the thousands of Mexicans in the U.S. military, serving can be a fast track to citizenship--if they survive.

The shrine in the corner would be familiar to many American military families. The flag is folded neatly in a triangle, encased in wood and glass. A couple of medals lie in boxes. A stern young man in his United States Army dress uniform peers out from a small photograph. His dog tags hang beside the photo. These are the relics of a life cut short in the name of honor, liberty, and country.

What seems odd is that the mementos are not in a living room in New Jersey or Nebraska, but in a house with concrete floors in a dusty town in central Mexico. And the soldier, Private First Class Jesus Fonseca, 19, was not an American citizen, but one of at least 25 Mexican citizens who have died fighting for the U.S. in two years of war.

About 28,000 permanent resident aliens were in the U.S. armed forces as of April--3,485 of them from Mexico. The Mexicans are the largest group among the 79 immigrants who have been killed in Iraq, the Pentagon says.

These numbers point to Mexico's ambivalent yet deeply intertwined relationship with the United States. Since 2000, more than 2.4 million Mexicans have migrated to the U.S. seeking jobs and a better life. Some of them, and now their children, are willing to fight and die for their new country.

For many, service in the armed forces is seen as a fast track to citizenship. During wartime, citizenship is all but guaranteed for foreigners who serve honorably in the American military, immigration officials say. In a cruel twist, soldiers like Fonseca, who died in Iraq on January 17 after taking a sniper's bullet in Ramadi, are accorded citizenship after death.

TWO WORLDS

Like Fonseca, most Mexicans in the armed forces straddle two worlds. Some join for the usual reasons: a desire for adventure, love for their adopted country, escaping poverty, a subsidized education, and the urge to prove themselves.

"The recruitment system really goes after the Hispanic community," says Fernando Suarez del Solar, whose son, Jesus, joined the Marines just out of high school. "A lot of Hispanics are born in Mexico but live in the United States and don't have citizenship. They see a good option in the Army to get papers, to get citizenship more quickly, and one thing the recruiters say often is that military service will make it easier for them to become accepted in society."

Jesus, 20, a lance corporal, was killed in March 2003 near Nasiriya, in the initial offensive in Iraq. He left behind a wife and infant son in Escondido, Calif.

For some, citizenship is less important than economic opportunity. Sergio Diaz Sr. says his son, Specialist Sergio Diaz Varela, 21, had few prospects when he graduated from Narbonne High School in Lomita, Calif. The father made a meager living doing odd jobs and fixing cars. They lived in a trailer park. "There weren't many other options, so he enlisted," Sergio Diaz Sr. says.

A DREAM DENIED

His son told relatives that someday he hoped to have a well-paid job in the States, as a full-fledged citizen. Then, he said, he wanted to buy his mother a house in Mexico. That dream ended last Thanksgiving in Iraq, when a roadside bomb in Ramadi killed him.

In December, he was buried in Mexico, outside Guadalajara. At first, his mother did not want the American flag draped over the coffin, but she relented under pressure from relatives.

Fonseca, too, had deep roots in Mexico, returning every summer. His father says his son had good grades in high school and could have gone to college but chose a military career instead. His goal was to become an intelligence officer.

"I'm proud of my son," his father says, "because even though he did not accomplish everything he want ed, it was still one of his dreams to belong to the Army."

Having gone to the U.S. as a toddler, Jesus Fonseca felt as much a part of the community in Marietta, Ga., where his family had settled, as he did part of Degollado, their hometown in Mexico. But it was during one of his summers in Degollado that he met his 18-year-old wife. After the war, they hoped to get citizenship and settle in Colorado.

Fonseca's Mexican grandmother fought back tears when asked whether she supported the war that had taken her grandson's life. "I don't know about politics," she says. "I can only say that it's a sad thing to see so many dead."

James C. McKinley Jr. In Mexico

This article is adapted from Friedman's book, "The World is Flat: A Brief History of the 21st Century," and his recent columns.

James C. McKinley is a correspondent in The Times's Mexico City bureau.