Minneapolis and St. Paul police officials were warned by the Department of Defense that military training exercises in the skies over the Twin Cities last year were a public relations near-disaster that threatened to sever their “future relationship,” according to internal documents obtained by a public watchdog group.

However, Minneapolis city leaders learned later that military officials told police to delay telling the public what was going on until the last minute, and then started the exercises before notice was given.

The papers were posted online by Public Record Media, a St. Paul-based nonprofit that uses freedom of information laws to get documents from federal, state and local government sources.

The subject of the data request was a five-day urban training mission, conducted with low-flying helicopters, that the Pentagon staged here last August.

Even though the mission had been in the works for eight months and approved by both mayors and high-ranking police officials, public notice wasn’t given until after surprised citizens spotted the Blackhawk helicopters flying between downtown skyscrapers and through residential neighborhoods.

After the resulting uproar, local and military officials huddled to craft a public statement while trying to contain the fallout — notably from a St. Paul City Council member who didn’t mince words.

“This was a boneheaded blunder from the start,” Dave Thune wrote in an e-mail to colleagues and city officials. “This was not a safe exercise. The last time there was an ‘accident’ involving an aircraft and a downtown office tower the NYC World Trade Center collapsed.”

The documents show that the exercises were directed by the Naval Special Warfare Development Group in Virginia Beach, Va., although a military spokesman told reporters that the helicopters belonged to an Army regiment based at Fort Campbell, Ky.

Thune said in his e-mail that “our excellent and trusted [St. Paul police] should not be engaging in military training,” which drew the attention of an unnamed military official who asked local police to keep a lid on “our trip” and “the training” as much as possible.

St. Paul, the military official wrote, “is already on the ‘cliff’ with their recent town councilman’s [Thune] actions. It must be controlled.”

To be sure everyone understood the mission was legitimate, the military official went on to cite federal documents that showed “Defense [Department] support of civilian law enforcement agencies” put the training “within US law.”

Asked Wednesday for his reaction to the e-mails, Thune said he was amused.

“Their paranoia was just stupid, and their lack of understanding about how civilian government works wasn’t inspiring at all. That’s what happens when the military brass call the shots,” he said.

“A lot of this could have been defused if they had just taken basic steps to notify the public on what they were doing,” said Matt Ehling, executive director of Public Record Media.