The popular imagination has often pictured the war veteran as a gregarious hero, eager to repeat a trove of cherished war stories. As a veteran of combat in World War II, I can only say that has not been my experience.

When my destroyer, the USS Lansdale, was nearly cut in two by a German torpedo, 49 of my shipmates were lost in that attack. But that was only the beginning of the toll. In the decades following, I witnessed the impact of combat trauma on the human psyche. Back then we called it battle fatigue. Today, psychiatrists call it post-traumatic stress disorder, or PTSD.

The most dramatic manifestation of PTSD among veterans now is a suicide rate approximately twice that of the general population. Anyone watching the recent presidential-campaign “commander in chief” forum heard the candidates cite repeatedly the estimate that each day, 22 military veterans take their own lives—and that far more of our servicemen and women will die at their own hand than at the hand of an enemy.

In 2012, the Department of Veterans Affairs announced an initiative to hire an additional 1,600 mental health professionals. Two years later, it announced another initiative to expand further the ranks. Last year, Congress passed, and the president signed, the Clay Hunt Suicide Prevention for American Veterans Act, named after a decorated Marine who killed himself in 2011 after struggling with PTSD.

But the bottom line is that despite these initiatives, the VA has not been able to expand its services to meet the need—and the tragic loss of life continues. In April, for instance, an assistant inspector general for Veterans Affairs, Larry Reinkemeyer, testified before Congress that the VA “struggles to attain and retain a sufficient mental health workforce capacity, establish a competency-based practice, and have adequate systems to support improving care nationwide.”

Even more troubling, Mr. Reinkemeyer said, even where the VA was able to expand the ranks of mental-health professionals, veterans were not experiencing a corresponding improvement in access to treatment. He also reported that the VA dropped the ball in its efforts to ensure that facilities used effective clinic management practices.

The VA is a tempting political target. It is expedient to paint the agency as a bloated and ineffective federal bureaucracy that has outlived its usefulness. I am decidedly not of that view.

The truth is that in many regions, and for many medical specialties, the VA is doing a commendable job, often providing more effective care than veterans could obtain elsewhere. Even with respect to mental health and PTSD, the VA is helping many veterans, and experimenting with private/public partnerships to provide innovative treatment.

But the time is long overdue to face an essential fact: Suicides by veterans have continued unabated, and the VA has not been able to meet the needs of those it serves.

It is time for Congress and the administration to take ownership of this issue. During the time that I was district attorney of New York County, a constantly rising homicide rate pivoted to a constantly declining homicide rate. It did so in no small part because we in law enforcement took as our goal not just expanding our efforts, but decreasing violence itself.

Similarly, we need to face frankly that current efforts to combat PTSD and suicide have been inadequate. To supply crucially needed mental health services, Congress and the administration need to act immediately to provide veterans access to civilian mental-health services, and need to improve treatment by dramatically expanding public/private partnerships. This must be a priority.

In 2014, when Barack Obama signed the Suicide Prevention for American Veterans Act, the president noted that, “[T]o every person in uniform, every veteran who has ever served, we thank you for your service. We honor your sacrifice. But sometimes, you know, talk is cheap.”

It is tempting to say that some things never change, but this is something that must change, and change now. We must expand mental-health options for our veterans and increase services. And we must not rest until the scourge of PTSD is defeated as soundly as any enemy we have ever faced on the field of battle.

Mr. Morgenthau, a former district attorney of New York County, is now of counsel at Wachtell, Lipton, Rosen & Katz.