Suicides among US Army soldiers more than doubled in July compared to June, the Pentagon said, the latest evidence of a worrisome trend that has vexed military leaders.

Among active-duty troops, 26 soldiers killed themselves last month, compared to 12 in June, according to an army statement.

The July toll was the highest for any single month since the Army began documenting suicides by month in 2009, officials said.

The army, which has borne the brunt of more than ten years of protracted ground wars in Iraq and Afghanistan, has suffered the highest suicide rates among all the US armed services.

Commanders have struggled to stem the problem, funding a myriad of programs and research to try to understand what is driving so many soldiers to take their lives.

"Suicide is the toughest enemy I have faced in my 37 years in the Army," said General Lloyd Austin, the US Army's vice chief of staff.

"That said, I do believe suicide is preventable," Austin said in a statement. "To combat it effectively will require sophisticated solutions aimed at helping individuals to build resiliency and strengthen their life coping skills."

The army reported 116 suicides through July of this year -- and if the current trend continues, the year's toll would far surpass the total of 167 for 2011.

Although officials suspect repeated combat deployments have contributed to a rise in mental health problems and suicide, a significant number of soldiers kill themselves who have never been in combat.

Senior officers have sought to allay fears among many troops that seeking out counseling could be seen as a sign of weakness and damage their career prospects.