Aboard a medical helicopter, Cpl. Andrew Smith of the Marines was treated by Sgt. Jaime Adame, top, an Army medic, after being seriously wounded in an attack in Helmand Province on May 15, 2011. Corporal Smith ultimately recovered from his injuries.

 

His war was almost over. Or so Marina Buckley thought when her son Lance Cpl. Gregory T. Buckley Jr. told her that he would be returning from southern Afghanistan to his Marine Corps base in Hawaii in late August, three months early.

 

Instead, Lance Corporal Buckley became the 1,990th American service member to die in the war when, on Aug. 10, he and two other Marines were shot inside their base in Helmand Province by a man who appears to have been a member of the Afghan forces they were training.

 

A week later, with the death of Specialist James A. Justice of the Army at a military hospital in Germany, the United States military reached 2,000 dead in the nearly 11-year-old conflict, based on an analysis by The New York Times of Department of Defense records. The calculation by The Times includes deaths not only in Afghanistan but also in Pakistan and other nations where American forces are directly involved in aiding the war.

 

Nearly nine years passed before American forces reached their first 1,000 dead in the war. The second 1,000 came just 27 months later, a testament to the intensity of fighting prompted by President Obama’s decision to send 33,000 additional troops to Afghanistan in 2010, a policy known as the surge.

 

In more ways than his family might have imagined, Lance Corporal Buckley, who had just turned 21 when he died, typified the troops in that second wave of 1,000. According to the Times analysis, three out of four were white, 9 out of 10 were enlisted service members, and one out of two died in either Kandahar Province or Helmand Province in Taliban-dominated southern Afghanistan. Their average age was 26.

 

The dead were also disproportionately Marines like Lance Corporal Buckley. Though the Army over all has suffered more dead in the war, the Marine Corps, with fewer troops, has had a higher casualty rate: At the height of fighting in late 2010, 2 out of every 1,000 Marines in Afghanistan were dying, twice the rate of the Army. Marine units accounted for three of the five units hardest hit during the surge.

 

The summer remained the peak season for fighting, and as has been the case since at least 2008, improvised explosive devices, known as I.E.D.’s, remained a leading cause of death and injury, along with small-arms fire, the analysis showed.

 

But this year, a new threat emerged: attacks by Afghans dressed in the uniforms of Afghan security forces. In just the past two weeks, at least 9 Americans have been killed in such insider attacks, and for the year to date, at least 39 non-Afghan troops, most of them American, have been killed by men dressed as members of the Afghan security forces, the most since the war began.

 

Those insider attacks have increased concerns about NATO’s ability to turn security operations over to Afghan forces by 2014, the deadline set by President Obama for withdrawing the remaining American forces. For families, the deaths have raised hard questions about whether the Pentagon is doing enough to protect its troops from their own allies.

 

None of that brings solace to the families of the dead. For the Buckleys, of Oceanside, N.Y., their son’s death so near the end of his tour, so late in the long war and possibly at the hand of a purported ally, was uniquely anguishing.

 

As Mrs. Buckley recounted things her son loved — basketball, girls, movies, the beach — bitterness choked her words.

 

“Our forces shouldn’t be there,” she said. “It should be over. It’s done. No more.”

 

Attacks From Afghans

Staff Sgt. Scott E. Dickinson was coming home early. He was originally scheduled to remain in Helmand until November 2012, but the Pentagon was pulling Marines out of Afghanistan quickly, looking to get the surge forces out of the country by fall and shrink the American footprint to about 70,000 troops. He would be home in Hawaii within a week or two, he told his father early this month.

 

Not long after that conversation, his father, John Dickinson, saw an article about a soldier who had died just a week before he was to come home. “I thought, ‘He’s not safe until he sets foot in Hawaii,’ ” recalled Mr. Dickinson, an architect in San Diego.

 

He was right. Sergeant Dickinson, 29, a supply specialist who had volunteered to help train Afghan forces, died with Lance Corporal Buckley on Aug. 10. They were among six Marines killed that day in two separate attacks by men who appeared to be Afghan security force members.

 

The Pentagon asserts that most of those attacks have been the result of personal grudges, disputing Taliban claims to have widely infiltrated the Afghan security forces.

 

But the attacks have also raised anew concerns about the integrity of the Afghan forces that NATO expects to secure the entire nation after NATO troops withdraw in 2014.

 

More fundamentally, the continued deaths, occurring even as American forces are conducting fewer combat missions, have prompted service members and military families to wonder: has the decade-long American presence in Afghanistan made a difference?

 

Colonel Morris, the former commander for the Third Battalion, Fifth Marine Regiment, has little doubt that it has. After months of fierce fighting, he saw clear changes when he left Sangin in early 2011. Those improvements remain, he asserts, with residents participating in elections and going to school with less fear of Taliban intimidation — though such intimidation is far from gone.

 

“Every single Marine in my battalion could see the impact they had,” he said. “It was a validation of everything they had sacrificed for.”

 

Despite his son’s death, Mr. Dickinson agrees. Marina Buckley is not so sure.

 

“He was the most lovable, caring human being,” she said of her son. “He wore his heart on his sleeve. Beautiful, beautiful, beautiful.”

 

He had wanted to join the Marine Corps ever since 9/11, despite her many attempts to dissuade him. By the time he was in high school a Marine Corps flag hung in his bedroom and her efforts to get him to go to college had failed.

 

“I’d say, ‘Why the Marines?’ ” she said, and he would reply with a joke. “I can pick up a lot of chicks with that uniform,” he would say.

 

But his ambition was serious: he wanted to serve, then become a police officer. He came to relish the brotherhood of the Marines and adored his first posting, in Hawaii. But deployment was different. The loneliness, the heat and the Meals Ready to Eat wore on him, Ms. Buckley said.

 

And he never felt secure living alongside Afghans, she said.

 

“If they want to kill themselves, let them,” she said of the Afghan people. “But they are killing people who shouldn’t be killed, who have lives here, and family here, and brothers and sisters here.”