A string of recent suicides among sailors assigned to the same U.S. aircraft carrier has sparked concern, prompting questions about mental health issues in the military and potential barriers to seeking treatment. 

Navy officials confirmed that at least four sailors assigned to the USS George Washington have died by suicide in the past year -- three of them in the past month. Retail Services Spec. 3rd Class Mikail Sharp was found dead April 9 at an off-base location in Portsmouth, Va.; Interior Communications Electrician 3rd Class Natasha Huffman was found dead April 10 in Hampton, Va.; and on April 15, Master at Arms Seaman Recruit Xavier Hunter Mitchell-Sandor was found unresponsive on board the ship in Newport News, Va., and later died, officials said.

The fourth sailor, who has not been publicly identified, died by suicide in 2021, and the cause of a fifth death that occurred last year is undetermined, according to officials.

"Each death is tragic in its own right," Pentagon press secretary John Kirby said during a news conference this week. "Our thoughts and prayers continue to go out to the families and, frankly, the shipmates because they're affected, too -- they're part of a sailors' family."

Mental health experts say the recent spate of suicides is concerning and raises questions about whether there are underlying issues in the military's culture contributing to the problem -- and how to fix them.

Experts say suicide deaths among service members have been a persistent problem since the wars in Afghanistan and Iraq but have been steadily climbing during the past several years. A Department of Defense report shows that there were 287 suicides in 2017 among active duty members in all branches of the military, 326 in 2018, 349 in 2019 and 386 in 2020. The number of suicides dropped in 2021 to 328, according to the report.

The coronavirus created unique stressors and, in fact, military suicides spiked during the pandemic, experts said.

Craig Bryan, a professor of psychiatry and behavioral health at Ohio State University, said suicide clusters are often a coincidence. But mental health experts also see them when there is an underlying factor affecting an entire group, and "some people who are perhaps more vulnerable kind of exceed the thresholds for suicide," he said.

The third and least-common scenario is when the suicides are directly linked to one another, Bryan said. Lt. Cmdr. Rob Myers, a public affairs officer with Naval Air Force Atlantic, said in a statement that the investigation is ongoing, but "there is no initial indication to suggest there is a correlation between these tragic events."

Sharp, Huffman, Mitchell-Sandor and the two sailors who have not been publicly identified were all assigned to the USS George Washington. The nuclear-powered, Nimitz-class aircraft carrier has been docked since 2017 at Newport News Shipbuilding in Newport News, Va., undergoing a major overhaul.

But oftentimes, it is not at the height of crisis - or combat - when members of the military start to experience mental health issues, said M. David Rudd, distinguished professor of psychology and director of the Institute for Veteran and Military Suicide Prevention at the University of Memphis.

"In the midst of crisis and in the midst of significant demands, people feel a real sense of purpose," he said.

"It's afterwards, it's in these periods where there's less activity, less to do, less purpose and less structure, that it creates opportunities for people to reflect and to feel and to think" about difficulties in other areas of their lives, Rudd said. In those times, problems tend to take on more emotional meaning, fueling depression, anxiety and substance use "that are always a part of the problem with suicide," Rudd explained.

Mental health experts agree that one limitation in preventing military suicides is that suicides are extremely complex, typically involving a number of factors, and there is rarely one explanation or solution. In addition, there are military policies and procedures that can make it more difficult -- not less - for those seeking help.

Rudd said one problem is that there is an inherent conflict between stated military values - courage, duty and selfless service -- and human vulnerabilities. "All of those things are wonderful and are appropriate in warrior culture. But the problem is it doesn't leave soldiers, and particularly young people, much room to be human when they have emotional problems or they have mental health challenges," he said.

Rudd said many facing mental health challenges say they feel a sense of failure for not meeting that standard.

Aside from that internal struggle, Rudd said another problem is that service members must generally disclose to superiors that they are seeking care from a mental health professional. "Those are things that, not purposefully, but just inadvertently, fuel shame and stigma that prevent people from asking for help at these critical times," he said.

Rudd said the military needs to look closely at policies that are in place that could create potential barriers.

As for the USS George Washington, Navy officials said there is a full medical team aboard the ship, including a psychologist and a corpsman who is qualified as a behavioral health technician.

Sharp, who was found dead April 9, was the first in the recent spate of suicides.

The 23-year-old, who joined the Navy nearly two years ago, had recently gotten married and was planning to buy a house and start a family, his mother, Natalie Jefferson, told NBC News.

Jefferson, who lived with her son in Norfolk, said she had no idea he was struggling, calling him "the life of the party."

"He never showed his pain," she told the network.

A day after Sharp's death, Huffman's body was found at an off-base location in Hampton, Navy officials said. She had joined the Navy in summer 2018.

In a heart-wrenching Facebook post, Huffman's mother, Kathleen Krull, wrote that her daughter "always stood up for the underdog" and that she was "fiercely protective of the people she loved."

"It still doesn't in some ways feel real to me that my baby girl is gone," Krull wrote.

Less than a year after Mitchell-Sandor joined the Navy, he was found unresponsive April 15 aboard the ship and was rushed to Riverside Regional Medical Center, where he died, CBS News reported.

Mitchell-Sandor, 19, had an affinity for sports. He had a black belt in karate and was the quarterback of his high school football team, according to his obituary. It was during his senior year that he enlisted and was sent to boot camp in Great Lakes, Ill., where he excelled as a leader yeoman and sharpshooter, his obituary stated.

He was stationed on the USS George Washington "where he protected the ship until his untimely death," it read.

Jefferson, Sharp's mother, urged other military members who may be struggling to get help "because the last thing any parent wants to do is bury their child," she said, according to NBC News.