KANSAS CITY, Mo. — Chalk up another national-security threat — this one looming with each excess pound, failing grade and drug bust affecting young adults. 

An alarming 75 percent of Americans ages 17 to 24 would not qualify for military service today because they are physically unfit, failed to finish high school or have criminal records. So says a new report from an organization of education and military leaders calling for immediate action on the early-education front.

While some experts voiced doubt that obesity and other societal ills would keep three out of four young adults out of the ranks, the report titled “Ready, Willing and Unable to Serve” was endorsed by U.S. Education Secretary Arne Duncan, former NATO commander Gen. Wesley Clark and top retired admirals and generals. 

“The armed services are meeting recruitment targets in 2009, but those of us who have served in command roles are worried about the trends we see,” retired Rear Adm. James Barnett said. “Our national security in the year 2030 is absolutely dependent on what’s going on in kindergarten today.” 

Military recruiters in Kansas City report turning away prospective recruits “in every office, every hour, every day” for reasons including girths too large and credit ratings too low. 

Increasingly, applicants are disqualified for having asthma or for taking pills for depression or attention disorders. Nearly one-third of all young adults have health issues other than weight that could keep them from serving, according to the report of the group Mission: Readiness. 

If you’re the single parent of a dependent child without a support network, you’re out. If you’re carrying too much debt, you’re out. The military doesn’t want recruits who will be hounded by creditors and lawsuits.

Some applicants without a high-school diploma can get a waiver to serve if they earn a GED or score high on the military’s entrance exam. But such waivers are granted to fewer than 2 percent of applicants. 

“What we allow waivers for, and for whom, is like an opening and closing gate depending on our needs. We can adjust our policies if we have to,” said Douglas Smith of the U.S. Army Recruiting Command.

As a slumping economy increases interest in military service, more people with obvious deficiencies are contacting recruiters. 

“We’re no longer so much saying, ‘Try back in 60, 90 days and see if you can qualify,’” Smith said. “It’s more like ‘We’re sorry ... and don’t come back.’ “ 

Even after signing up, 7 to 15 percent of enlistees return home for not meeting all that basic training demands. 

“It’s not that the military is hard to get into,” said Darin Eash, a Navy chief hull technician at Kansas City’s Military Entrance Processing Station in Missouri. 

“It just all comes down to the individual,” such as one potential recruit, an honor student, who failed a morning aptitude test apparently because he’d had little sleep — a trend Eash has noticed among young adults that he said might hurt their ability to perform.

The applicant re took the test in the evening and aced it. 

Then there was the overweight cook from Joplin, Mo., who in his months-long quest to slim down showed up every week at the recruiting station to step on the scale. 

“I transferred out before I could see if he ever made it,” Eash said. 

Obesity alone disqualifies 27 percent of all young Americans from serving. About one in four in the 17-to-24 age group lacks a high school diploma. 

Delaware, Florida, Georgia and Texas posted unusually high rates of obesity, juvenile crime and dropout rates. 

“To say 75 percent of an entire age group would be ineligible to serve, that sounds too high,” said John Pike of the defense think tank GlobalSecurity.org, echoing the initial reaction of other military watchers and some recruiters in Kansas City. “But it wouldn’t be off the mark in some communities,” including low-income areas historically attracted to career and education opportunities offered by joining the volunteer fighting forces.

“When looking for officer candidates, they’re trying to recruit the high-school quarterback, not the slacker under the bleachers smoking a cigarette,” Pike said. “Someone who dropped out of school and got supersized? You have a hard time seeing a soldier there.” 

Just to bring one airman into the military, Air Force recruiters report having to make contact with 110 people who show an interest in joining. Still, the Air Force has met monthly recruiting goals for 10 years running.

“With the shift in the economy, we’re seeing a shift in the number of people trying to get in and a higher level of those who disqualify,” said Christa L. D’Andrea, public affairs chief for the Air Force Recruiting Service. 

For the high schoolers at Wentworth Military Academy in Lexington, Mo., some of whom were low achievers in previous schools, daily physical activity is required after classes end. 

“At 4 o’clock, you can’t be playing Xbox 360,” said principal Bob Levy. 

The average ACT score at Wentworth last school year was 26, almost five points higher than the national average for college-bound students. 

Mission: Readiness organizers, including Education Secretary Duncan, are pressing Congress to approve the Early Learning Challenge Fund, which would provide $1 billion annually in grants to states for 10 years to improve childhood development programs. 

“The sophistication of our military is increasing every year so we will soon need even better-qualified recruits,” said retired Gen. Hugh Shelton, former chairman of the Joint Chiefs of Staff. “We need to ensure all young Americans get the right start in life.”