Defense Secretary Ashton Carter withheld comment Sunday on the Iraq war veteran charged with the Fort Lauderdale shootings while stating that post traumatic stress was a major and ongoing problem for the military.

"The mental wounds are very real" for many returning troops in the 15 years of war since the Sept. 11, 2001, terror attacks in New York City and Washington, D.C., Carter said on NBC's "Meet The Press" program.

"I can't say" what may have motivated the Fort Lauderdale shooter or comment on his mental stability, the secretary said, but "the so-called invisible wounds" of combat were conditions "we do take seriously and have to take seriously.

"It matters a great deal to me that we take care of wounded warriors," Carter added. "We keep learning more about how to deal with this kind of illness, we're going to do more and we need to do more as we learn more, absolutely. We owe it to these people."

Members of the family of 26-year-old Esteban Santiago, an Army National Guard veteran of Iraq, have told the Associated Press that Santiago returned from Iraq a different person and was deeply distraught over witnessing the deaths of two friends from an improvised explosive device.

It was unclear Sunday whether Santiago had been given or requested legal representation, or whether mental competence might be used as a defense to federal charges that could bring the death penalty.

Santiago was the sole suspect in the shootings Friday in the baggage claim area of the Fort Lauderdale-Hollywood International Airport in Florida that killed five and injured at least six.

Santiago served with the Puerto Rico Army National Guard in Iraq from April 2010 to February 2011 as a combat engineer and was involved in route clearance, according to the Defense Department and the Army.

His dates of service were from December 2007 to August 2016. He was a recipient of the Combat Action Badge, a Pentagon spokesman said. Santiago left the Puerto Rico National Guard in 2013 and later re-entered service with the Alaska National Guard, the spokesman said.

Last August, Santiago received a general discharge under honorable conditions for "continuous and willful absence" from his duties with the Alaska National Guard, the spokesman said. His rank was reduced from Specialist to Private First Class upon discharge.

The Department of Veterans Affairs handed out more than $30 million in employee incentives in one year without justification, and it will continue to overspend if changes aren't made, according to a report released Jan. 5 by the agency's internal watchdog.

The findings are the result of an investigation by the VA inspector general's office into how the department was using funds to attract and retain employees. Inspectors initiated the investigation after allegations that the department was giving out too many incentives to VA executives without cause -- a charge Republican lawmakers and VA leaders have quarreled about in recent years.

"The VA has limited assurance that it is using [recruitment, relocation and retention] incentives effectively and strategically to acquire and retain talent," the inspectors' report stated.

Inspectors found $30.7 million of $66 million spent in fiscal 2014 to recruit, relocate or retain employees was not fully justified. At that rate, they estimated the VA could give out $158.7 million in unsupported incentives through September 2019. Inspectors concluded VA officials did not always confirm the incentives were being used to help fix workforce gaps or were necessary to recruit and retain employees.

The VA also failed to recoup about $784,000 of incentives that were awarded on conditions that employees then did not meet. Inspectors estimated the VA could fail to collect another nearly $4 million through fiscal 2019.

Meghan Flanz, acting assistant secretary for VA human resources and administration, responded to the report by saying her office has started to take corrective measures and the department has already updated some of its procedures and internal controls to avoid giving out incentives haphazardly.

The findings were issued about two weeks after Deputy VA Secretary Sloan Gibson sent a letter to Congress urging lawmakers lift spending restrictions on employee bonuses that were put in place last year.

Limits on how much the VA could spend on bonuses and other awards to employees were worked into the Comprehensive Addiction and Recovery Act of 2016, which addresses the nationwide opioid epidemic.

Gibson called the restrictions "counter-productive," "unwarranted" and a hindrance in hiring and retaining high-quality employees. Because of them, he said, employees would see a 30-percent cut in performance-based awards this fiscal year.

"[It] defies logic that Congress should so severely limit employee awards and incentives, for VA alone, at such a pivotal time in our transformation," Gibson wrote.

With confirmation hearings for Donald Trump’s Cabinet set to start this week, the president-elect still has not chosen a leader for the Department of Veterans Affairs, an agency he vowed on the campaign trail to significantly shake up.

It is not for lack of trying.

Trump has met with or considered about a dozen candidates to run the second-largest federal department. But none seems to have made the cut.

Of all the day-to-day operations of government that Trump railed against during his campaign, VA, an agency reeling from scandal, came under special scrutiny. Its management challenges are vast, and the president-elect’s promises to veterans to remake it daunting.

Finding the right person for the job — and someone who actually wants it — remains one of Trump’s biggest challenges less than two weeks before his inauguration. VA is one of only two Cabinet positions — the other is the Agriculture Department — without a nominee for secretary.

In recent weeks, Trump has met with retired military leaders, politicians and health-care executives, some of whom would help diversify a Cabinet he is under pressure from some on his team to make more inclusive. He has met with some candidates multiple times and extended preliminary offers to others. Yet several qualified contenders have turned him down.

Reince Priebus, Trump’s incoming chief of staff, has urged the president-elect to expand the VA search to more women and minorities, according to a source close to the transition who spoke on the condition of anonymity because the person was not authorized to discuss internal discussions publicly.

Trump met last week with Leo MacKay Jr., a senior vice president at Lockheed Martin who was a deputy VA secretary under President George W. Bush. But MacKay, who is black, is reluctant to leave the private sector, the source said. In December, Trump officials approached Navy Adm. Michelle Howard, the first woman and African American to become a four-star admiral. But she declined to pursue the post.

VA, with 360,000 employees, an $180 billion budget, and a sprawling system of 1,700 medical centers and benefits, has proven one of the toughest corners of the government to run — and run well. Its daily operations are tested by the burdens of 15 years of war in Iraq and Afghanistan and increasing medical demands from older veterans who fought in Vietman, Korea and World War II.