Last week's deadly shooting at Fort Hood, Texas, the second mass shooting in five years at the Army post, has focused renewed attention on the challenges faced by military veterans returning from war.
Many veterans surveyed said they found re-entering civilian life to be difficult.
A significant share reported having experienced outbursts of anger in daily life after serving.
Others say their mental or emotional health is worse since their time in the service, or that they have suffered post-traumatic stress disorder.
More than a third of all post-9/11 war veterans reported suffering from post-traumatic stress syndrome, in a 2011 Pew Research survey.
These problems loom at a time when the suicide rate has risen among military personnel.
The Post/Kaiser survey found more than half of Iraq and Afghanistan veterans it surveyed personally knew a service member or veteran from those wars who had attempted or committed suicide.
Including members of the Reserve and National Guard, more service members killed themselves last year than died in combat.
The suicide rate of National Guard soldiers and Reservists nearly doubled in the last year alone, and statistics suggest that Minnesota has one of the higher rates in the nation. Overall, military suicides have hit record levels, the Star Tribune reports.
"Simply stated, we are often more dangerous to ourselves than the enemy," a 2010 Army report concluded.
The guard touts its suicide prevention program as having prevented 37 suicides last year.
The guard says it's found the causes of suicide among guard members to include employment and relationship problems, mental health and substance abuse issues and financial trouble.
It's not necessarily what the individual is facing on deployment, but facing back home,'' Lt. Col. John Echert, senior chaplain at the Minnesota Air National Guard's Minneapolis-based 133rd Airlift Wing, told the Star Tribune.
More soldiers also seem to be entering the ranks with a propensity toward high-risk behaviors of all types.
A recent study – the largest-ever – of soldiers and suicide, published in the the journal JAMA Psychiatry, found one-third of suicide attempts in the Army were linked to a condition the soldier had before enlisting.
Pre-existing conditions could include problems like attention deficit disorder, substance abuse, explosive violent anger or rage, NPR News reports.
After last week's shooting, some veterans expressed concern over barriers veterans face in seeking help for mental health conditions.
The Fort Hood gunman, who killed three people and wounded 16 other soldiers before taking his own life last week, has been identified as Specialist Ivan A. Lopez.
Lopez served in Iraq in 2011 and had been under evaluation for post-traumatic stress disorder. The Army says he was also being treated for anxiety and depression.
Military officials say Lopez, had not seen combat during a relatively short tour, and there are reports of other factors that may have been in play, including a dispute with superiors over a request for leave, The Washington Post reports.