In Nebraska’s open U.S. Senate race, where the winner of the Republican primary is expected to win the seat fairly easily, the top two GOP candidates are Midland University President Ben Sasse and former state Treasurer Shane Osborn. They’re both very conservative – in fact, prominent far-right activist groups are split between them – though there’s one big difference between them.

Osborn is a military veteran, which is a part of his background he’s been eager to emphasize . Unexpectedly, though, it’s this signature element of Osborn’s biography that seems to be causing him the most trouble.

In 2001, during something called the Hainan Island incident , Osborn piloted a Navy EP-3 reconnaissance plane over China, which collided with a Chinese Navy jet, forcing Osborn to make an emergency landing. Osborn was interrogated and released after 12 days. (China returned the U.S. reconnaissance plane slowly and in pieces, after studying its components and reverse-engineering its technology.)

Because Osborn has made his military service such an important part of his campaign, the Hainan Island incident has generated a fair number of questions. To help resolve the matter, the Republican’s campaign distributed an official-looking Navy memo supporting his account of what transpired.

But as it turns out, it wasn’t actually a Navy memo (thanks to my colleague Tricia McKinney for the tip).

The memo, written Aug. 8, 2013, on Navy letterhead, is titled “Disposition of actions by EP-3E flight crew on April 1, 2001.” It explains that Osborn’s plane was authorized to land on China’s Hainan island “due to the extreme circumstances and condition of this aircraft.” But The World-Herald has learned that the unsigned memo was not authorized by the Navy, or vetted through normal channels, and was written as a favor to Osborn by a Navy buddy working at the Pentagon.

“We cannot confirm the authenticity of this document,” Lt. Cmdr. Katie Cerezo, a Navy spokesperson, told the Omaha paper. “We couldn’t discuss a memo that we can’t authenticate.”

And that’s a bit of a problem.

Some of Osborn’s critics have suggested he shouldn’t have landed the reconnaissance plane in China, though he insists his decision saved the lives of his crew. Given the circumstances, it’s probably a legitimate area of discussion.

But trying to shut the debate down with a fake Navy memo generally makes matters worse, not better.

We don’t yet know the name of the official who wrote the memo as a favor – he or she is apparently concerned about career repercussions – but the author told the Omaha paper, “We didn’t do anything wrong. But we did it to sort of shortcut the process.”