WASHINGTON – Suicides are surging among America’s troops, averaging nearly one a day this year — the fastest pace in the nation’s decade of war.

The 154 suicides for active-duty troops in the first 155 days of the year far outdistance the U.S. forces killed in action in Afghanistan — about 50 percent more – according to Pentagon statistics obtained by The Associated Press.

The numbers reflect a military burdened with wartime demands from Iraq and Afghanistan that have taken a greater toll than foreseen a decade ago. The military also is struggling with increased sexual assaults, alcohol abuse and domestic violence.

Because suicides had leveled off in 2010 and 2011, this year’s upswing has caught some officials by surprise.

The reasons for the increase are not fully understood. Among explanations, studies have pointed to combat exposure, post-traumatic stress, misuse of prescription medications and personal financial problems. Army data suggest soldiers with multiple combat tours are at greater risk of committing suicide, although a substantial proportion of Army suicides are committed by soldiers who never deployed.

The unpopular war in Afghanistan is winding down with the last combat troops scheduled to leave at the end of 2014. But this year has seen record numbers of soldiers being killed by Afghan troops, and there also have been several scandals involving U.S. troop misconduct.

The 2012 active-duty suicide total of 154 through June 3 compares to 130 in the same period last year, an 18 percent increase. And it’s more than the 136.2 suicides that the Pentagon had projected for this period based on the trend from 2001-2011. This year’s January-May total is up 25 percent from two years ago, and it is 16 percent ahead of the pace for 2009, which ended with the highest yearly total thus far.

Suicide totals have exceeded U.S. combat deaths in Afghanistan in earlier periods, including for the full years 2008 and 2009.

The suicide pattern varies over the course of a year, but in each of the past five years the trend through May was a reliable predictor for the full year, according to a chart based on figures provided by the Armed Forces Medical Examiner.

The numbers are rising among the 1.4 million active-duty military personnel despite years of effort to encourage troops to seek help with mental health problems. Many in the military believe that going for help is seen as a sign of weakness and thus a potential threat to advancement.

Kim Ruocco, widow of Marine Maj. John Ruocco, a helicopter pilot who hanged himself in 2005 between Iraq deployments, said he was unable to bring himself to go for help.

“He was so afraid of how people would view him once he went for help,” she said at her home in suburban Boston. “He thought that people would think he was weak, that people would think he was just trying to get out of redeploying or trying to get out of service, or that he just couldn’t hack it — when, in reality, he was sick. He had suffered injury in combat and he had also suffered from depression and let it go untreated for years. And because of that, he’s dead today.”

Jackie Garrick, head of a newly established Defense Suicide Prevention Office at the Pentagon, said in an interview Thursday that the suicide numbers this year are troubling.

“We are very concerned at this point that we are seeing a high number of suicides at a point in time where we were expecting to see a lower number of suicides,” she said, adding that the weak U.S. economy may be confounding preventive efforts even as the pace of deployments eases.

Garrick said experts are still struggling to understand suicidal behavior.

“What makes one person become suicidal and another not is truly an unknown,” she said.

Dr. Stephen N. Xenakis, a retired Army brigadier general and a practicing psychiatrist, said the suicides reflect the level of tension as the U.S. eases out of Afghanistan though violence continues.

“It’s a sign in general of the stress the Army has been under over the 10 years of war,” he said in an interview. “We’ve seen before that these signs show up even more dramatically when the fighting seems to go down and the Army is returning to garrison.”

But Xenakis said he worries that many senior military officers do not grasp the nature of the suicide problem.

A glaring example of that became public when a senior Army general recently told soldiers considering suicide to “act like an adult.”

Maj. Gen. Dana Pittard, commander of the 1st Armored Division, last month retracted — but did not apologize for — a statement in his Army blog in January. He had written, “I have now come to the conclusion that suicide is an absolutely selfish act.” He also wrote, “I am personally fed up with soldiers who are choosing to take their own lives so that others can clean up their mess. Be an adult, act like an adult, and deal with your real-life problems like the rest of us.” He did counsel soldiers to seek help.

His remarks drew a public rebuke from the Army, which has the highest number of suicides and called his assertions “clearly wrong.” Last week the chairman of the Joint Chiefs of Staff, Army Gen. Martin Dempsey, said he disagrees with Pittard “in the strongest possible terms.”

The military services have set up confidential telephone hotlines, placed more mental health specialists on the battlefield, added training in stress management, invested more in research on mental health risk.

The Marines established a counseling service dubbed “DStress line,” a toll-free number that Marines can call anonymously. They also can use a Marine website to chat online anonymously with a counselor.

As part of its prevention strategy, the Navy has published a list of “truths” about suicide: “Most suicidal people are not psychotic or insane,” it says. “They might be upset, grief-stricken, depressed or despairing.”

In a report published in January the Army said the true impact of its prevention programs is unknown.

“What is known is that all Army populations … are under increased stress after a decade of war,” it said.

Marine Sgt. Maj. Bryan Battaglia, the senior enlisted adviser to the chairman of the Joint Chiefs of Staff, recently issued a video message to all military members in which he noted that suicides “are sadly on the rise.”

“From private to general, we shoulder an obligation to look and listen for signs and we stand ready to intervene and assist our follow service member or battle buddy in time of need,” Battaglia said.