(CNN) Over 1,000 active duty US Army soldiers have died by suicide since 2015, and a new study suggests that reducing those deaths may require limiting access to one of a soldier's most familiar tools: the gun.

The research, published Friday in the medical journal JAMA Network Open , found that soldiers who died by suicide were more likely than their peers to own personal firearms. Storing a loaded gun at home or carrying one in public, the study found, was "associated with a 4-fold increase in the odds of suicide death" among soldiers.

The findings come at a tense time for the military, with suicides among active-duty Marines and sailors reaching a 10-year high last year and suicides among US Special Operations forces tripling . About two-thirds of all active duty suicides involve a gun, according to the Department of Defense's most recent annual report

"I think the main points of this study are that certain behaviors related to ownership of firearms are associated with an increased risk of completing suicide," said Army Col. David Benedek, a co-author on the study and chair of the department of psychiatry at the Uniformed Services University, a federal military academy.

Funded by the US Department of Defense and the US Department of Health and Human Services, the research is part of a larger effort launched in 2009 to understand suicide among service members. The results, experts say, mean that any conversation on suicide risk cannot be limited to mental health alone.

"It's important to note that having access to a firearm doesn't make somebody suicidal," said Michael Anestis, an associate professor of psychology at the University of Southern Mississippi who was not involved with the study. "It's not that access to a gun puts the thought in someone's head and makes them suicidal."

Instead, Anestis said, "the idea is that suicide is hard, and people tend to, when they make an attempt, use something they feel comfortable with and confident they can use, and which they've thought about before." That's why the majority of suicide attempts are intentional overdoses, Anestis notes, because most people are familiar with taking medicine.

But those who regularly interact with guns -- especially people in the military -- have ready access to, and experience with, a far more lethal tool that others may not feel comfortable using.

An estimated "85 to 95% of suicide deaths with a firearm are lethal," Anestis said, "whereas only 2 to 3% of intentional overdoses are." In soldiers, then, "the role of a firearm essentially displaces medicine or some other method that has a lower lethality rate."

That means that access to a gun can be the difference between life and death, said Dr. Paul Nestadt, an assistant professor of psychiatry at Johns Hopkins University who was not involved in the study.

"There is a common misconception out there that if you're suicidal, you'll just find a way," he said. "Or that if you don't die in your first attempt, you'll die in another. The evidence does not show that happening."

'Psychological autopsies'

The study looked at 135 soldiers who died by suicide, and compared them to 137 living soldiers with similar demographic backgrounds and suicide risk factors, such as the number of times they had been demoted and their history of injury. All of the soldiers were active duty, but stationed in the United States and not deployed at their time of death.

To complete "psychological autopsies," the research team asked family members and supervisors about the gun ownership history of those who died: how many firearms they had, when they carried them and how they were stored.

That technique, Nestadt said, offered researchers reliable information on the firearm habits of those involved in the study. "They got to speak directly with next-of-kin, got to know each case individually, and got really detailed information confirmed by the family," he said.

When those who died by suicide were compared to a second, smaller control group -- which included 108 living soldiers who had expressed suicidal thoughts in the past year -- the differences in gun usage did not reach statistical significance. But Nestadt attributed this mostly to sample size. "There is every implication that the suicidal ideation group would also have had a significant correlation with firearm access had the sample been larger," he said.

Dr. Joseph Simonetti, an assistant professor of medicine at the University of Colorado School of Medicine, also emphasized that the study's methodology was rigorous. And the findings from the study overall, he said, were straightforward: The easier it is to get to a gun, the higher the risk that a soldier may die by suicide.

"The reality is that removing a firearm from a home is likely to be the safest thing someone can do to prevent suicide," Simonetti said, "but [the study] provides some support that for those only willing to make safety changes within the home, such as locking their guns and leaving them unloaded, that can also reduce their suicide risk."

A dangerous thought can become reality

Dr. Dean Winslow, a physician and retired Air Force colonel who now teaches at Stanford, regularly saw suicide deaths while on duty, often signing preliminary death certificates while working at a combat hospital in Baghdad. Many times, he said, the suicides were triggered by a life-changing event such as the end of a relationship.

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"If we don't have ready access to a firearm," Winslow said, "we stop, we might pick up the phone or walk down the hall, talk to a buddy, or go out to a bar and have some drinks, and the thought passes, and you start coming out of it."

But when people have a loaded weapon nearby -- as soldiers often do -- that passing thought can quickly become a reality. And while the study was conducted in the military, Winslow says the findings can apply to the civilian population.

"It becomes just too easy to actually do it," said Winslow, who has advocated for increased gun regulation. "And of course you can't take it back. It's not like swallowing a pack of pills, where there's a good chance that someone may find you and they'll take you to the hospital and pump your stomach and you'll survive.

"If you put a gun to your head and pull the trigger," he said, "you're not going to survive."