The killing of at least 13 people in the heart of America's military network in Fort Hood, Texas, is very hard to bear.

Losses in the wars in Iraq and Afghanistan, now surpassing 5,000, are deaths also, endured and grieved by families, friends and citizens. But Thursday's events, occurring in what passes for home for hundreds of thousands of U.S. troops and their families, is sharply inflicted pain.

Making sense of what happened -- if that is possible -- will take time and require further knowledge of the apparent killer and the circumstances that led to this disaster. It will not help the country that Maj. Malik Nidal Hasan, the person who likely will be charged with the killings, is apparently a fervent Muslim, with family roots in the Middle East, the locus of the two wars and the scene of some of the most severe violence that has afflicted the world for the last six decades.

Another factor to examine in trying to understand what happened is the degree to which members of America's professional army have been stressed and stretched by a six-year war in Iraq and an eight-year war in Afghanistan. Soldiers have been sent on repeated tours of duty in difficult, hostile circumstances with only brief respites at home between deployments.

This overuse of the volunteer military is due to the fact that the nation's elected leaders know Americans would not tolerate a draft to supply troops for the two wars.

While Maj. Hasan had not served in Iraq or Afghanistan and was deeply opposed to the U.S. role there, he was on the eve of his first deployment -- to Afghanistan. As an Army psychiatrist, he worked for six years, until last July, as a liaison between wounded soldiers and psychiatric staff at Walter Reed Army Medical Center in Washington, D.C. He heard their stories and was well acquainted with their pain.

There is no justification, however, for the injury and death that he apparently perpetrated, and his family was right to denounce the act as "despicable and deplorable."

There is no point in criticizing Fort Hood. It is considered to be a model of a military base. At the same time, Killeen, Texas, where it is located, is a typical military town, with streets of payroll loan, pawn and gun shops serving a largely transient, not well-paid population.

At this point, Americans can only regret what happened at Fort Hood and grieve for those lost and their loved ones.

Cartoonist Rob Rogers does "Rob's Rough," an early look at his work and his creative process, exclusively at PG+, a members-only web site of the Pittsburgh Post-Gazette. Our introduction to PG+ gives you all the details.