Washington (CNN) -- May was the worst month in a year for suicides and potential suicides in the active-duty Army, the Pentagon announced Thursday.
The Army reported 21 potential suicides among active-duty soldiers in May. One of them has been confirmed; the other 20 are under investigation. In the past, most of the cases investigated were confirmed to be suicides.
May's number was the highest for one month since June 2010, which at the time was the worst month in recent memory for Army suicides.
There were also 21 potential suicides among active-duty soldiers in June 2010, but that month also saw 11 potential suicides among the Guard and Reserves. Last month, there were six potential suicides in the National Guard and Reserves, so June 2010 remains worse.
The latest data continue to show that suicide statistics in the Army frequently fluctuate. April saw 16 potential suicides, more than twice the number in March, when seven cases were investigated.
The Army says it's tough to know why suicide cases increase even as the entire Pentagon is trying to solve the problem. But spokesman Lt. Col. Steve Warren said, "a spike in cases does not necessarily mean a trend."