Washington (CNN) Deaths by suicide in the US military continue to rise with 541 service members dying in 2018, according to a Pentagon report issued Thursday.

Military leaders are continuing to express concern and frustration about the rising number of deaths as they attempt to understand why the numbers are increasing.

"I wish I could tell you we have an answer to prevent further, future suicides in the armed services. We don't. We are caught up in what some call a national epidemic of suicide among our youth. And not just our youth, but it's something we continue to wrestle with," Defense Secretary Mark Esper told reporters Wednesday.

There were 511 deaths by suicide in 2017, and there was a particular increase in 2018 among active duty service members.

325 suicides were reported in the active duty ranks in 2018, up from 285 in 2017 and 280 in 2016. In the reserves, there were 81 suicides reported in 2018, down from 93 in 2017 with 80 in 2016. In the National Guard, there were 135 cases in 2018, compared to 133 in 2017 and 122 in 2016.

Read More