Those who went to war after Sept. 1, 2001, are different than the generations of veterans who went before them, and are "more likely to bear the scars of battle," both physical and mental.

"Their collective experiences -- from deployment to combat to the transition back to civilian life -- are markedly different from those who served in previous eras," according to a unique survey by the nonpartisan Pew Research Center, released Tuesday on the eve of the 18th anniversary of the 9/11 attacks.

"Roughly half of post-9/11 veterans (49%) have had combat experience, compared with 24% of veterans who served only before 9/11," the survey found.

The survey of more than 1,200 veterans and, separately, more than 1,000 adult civilians examined the veterans' own assessments of what they experienced in battle and the transition out of uniform, contrasting that with the civilians' views of the returning service members.

Related: Post-9/11 Vets Have Far Higher Disability Ratings Than Prior Generations: Report

According to Pew's statistics, those who served after 9/11 now make up about one-fifth of the nation's more than 20 million veterans. About 75% of them deployed at least once, compared to 58% of pre-9/11 veterans, and they were twice as likely to have served in a combat zone, the survey found.

"Because they are more likely to have been deployed and to have seen combat, post-9/11 veterans are also more likely to bear the scars of battle," the survey says.

"Roughly half say they had emotionally traumatic or distressing experiences related to their military service, and about a third say they sought professional help to deal with those experiences," according to the survey.

The National Center for PTSD at the Department of Veterans Affairs estimated last year that 11% to 20% of those who served in Iraq and Afghanistan experienced Post-Traumatic Stress Disorder, but the Pew survey found that 36% of the post-9/11 veterans believe they suffered from it.

Majorities of all veterans are proud of their service, the survey found, but "those who served in the post-9/11 era are somewhat less likely than their predecessors to say they frequently felt proud after leaving the military (58% vs. 70%)."

In addition, post-9/11 veterans "are more likely to say they didn't get the respect they deserved, struggled with the lack of structure in civilian life, and felt disconnected from family or friends," according to the survey.

"About half of post-9/11 veterans say it was somewhat or very difficult for them to readjust to civilian life after their military service," compared to about 20% of pre-9/11 veterans, the survey found.

Nearly one-third of post-9/11 veterans said they had trouble paying bills after leaving the service, and about 30% said they received unemployment compensation, it adds.

The differing views of veterans and the general public emerged in the survey's findings on the use of the term "patriotic" and whether serving in the military is a good career choice.

A large majority of post-9/11 veterans (71%) said that the term patriotic better described those who served than those who did not, while 58% of the public shared that view. About one-third of the civilians surveyed said that patriotism isn't related to veteran status.

One of the major differences between the views of post-9/11 veterans and civilians found in the survey was on whether they would advise a young person close to them to join the military.

About 8 in 10 of the veterans said they would, while about half of the general public said they would not, the survey shows.

"The American Veteran Experience and the Post-9/11 Generation" survey of 1,284 U.S. military veterans was conducted online from May 14 to June 3 this year. The parallel survey of 1,087 U.S. adults was conducted from May 14 to May 24.

When asked whether the VA and other government agencies provide adequate assistance, post-9/11 veterans "are more likely than those from previous eras to say the government has given them less help than it should have (43% vs. 27%)," the survey found.

On employment after service, 42% of post-9/11 veterans said they believe, based on their experience, skills and training, they were overqualified for their first post-military job, and 56% said they stayed in their first job for more than a year, according to the survey.

The 34-page Pew report on the survey said the findings overall show that post-9/11 veterans are reshaping "what it means to be a military veteran in the United States," and pointed to the need for the military to put more focus on the transition to civilian life.

About 90% of both post-9/11 and pre-9/11 veterans said the military had prepared them well for the missions they were given.

"However, they are less affirmative about the job the military did preparing them for the transition to civilian life," the survey says.

"About half of all veterans say the military prepared them very or somewhat well," but "a similar share says the military didn't prepare them too well or at all," it found.

The full survey can be found here.

-- Richard Sisk can be reached at Richard.Sisk@Military.com.

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