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 146 suicides for active-duty troops in the first 148 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, domestic violence and other misbehavior.

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. There also have been several scandals involving U.S. troop behavior.

The active-duty suicide total through May 27 compares to 125 in the same period last year, a 17 percent increase. And it's more than the 129.6 suicides that the Pentagon had projected for this period based on the trend from 2001-2011. This year's January-May total is up 24 percent from two years ago, and it is 15 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. Despite those efforts, many in the military believe that going for help is seen as a sign of weakness.

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 in an interview 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 military 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 also 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 and taken other measures.

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

The Marines arguably have had the most success recently in lowering their suicide numbers, which are up slightly this year but are roughly in line with levels of the past four years. The Army's numbers also are up slightly. The Air Force has seen a spike, to 30 through May 27 compared to 21 at the same point last year. The Navy is slightly above its 10-year trend line but down a bit from 2011.

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, adding that if not for prevention efforts the Army's suicide totals might have been as much as four times as high.

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.

The suicide numbers began surging in 2006. They soared in 2009 and then leveled off before climbing again this year. The statistics include only active-duty troops, not veterans who returned to civilian life after fighting in Iraq or Afghanistan. Nor does the Pentagon's tally include non-mobilized National Guard or Reserve members.

The renewed surge in suicides has caught the attention of Defense Secretary Leon Panetta. Last month he sent an internal memo to the Pentagon's top civilian and military leaders in which he called suicide "one of the most complex and urgent problems" facing the Defense Department, according to a copy provided to the AP.

Panetta touched on one of the most sensitive aspects of the problem: the stigma associated seeking help for mental distress. This is particularly acute in the military.

"We must continue to fight to eliminate the stigma from those with post-traumatic stress and other mental health issues," Panetta wrote, adding that commanders "cannot tolerate any actions that belittle, haze, humiliate or ostracize any individual, especially those who require or are responsibly seeking professional services."