Unintentionally handing over military hardware to the enemy - any precedents?

This subject is being discussed in a parallel thread:

Is there any precedent for such a mishap, outside of a combat situaton, occurring in the past? I have heard about secret informations being inadvertently published by government agencies, but shipping a significant piece of hardware via parcel to the enemy (sort of) seems highly unusual.

Everything illegally leaked by Assange, Manning, Snowden, etc…should count. In many ways, information is much more useful to an enemy than a physical asset.

So, in this regard, yes; it’s happened millions of times.

There’s a well publicized incident in which the US sold AWACS aircraft to Israel, and critical technology was then sold to China.

Well, I imagine that if America wanted to sell to Country X ( China in this case, which is not an enemy ) but was constrained by politics from doing so, selling it through a middleman might be the way to go.

It was war time, but the loss of HMS Seal ( with the surround context suggesting its mission was far to dangerous, far too suicidal… ) gave Deutchland vital technological knowledge, its torpedo’s control mechanisms…

No. The technology was supposed to remain a secret from China so they couldn’t exploit it.

That sounds like a mishmash of a couple real events.

“AWACS” is an acronym that refers strictly to the Boeing E-3A aircraft. AEW (“airborne early warning”) is the generic term for similar aircraft built by any country or manufacturer. Many sloppy sources use AWACS in the generic sense, but that’s not correct and is misleading.
The Israelis have a pretty good radar industry of their own. Russia had built an AEW aircraft called the Be A-50. In cooperation with Russia Israel installed one of their indigenous advanced radar designs on a Russian Be A-50 AEW airframe for sale to India. See https://en.wikipedia.org/wiki/Beriev_A-50

Subsequently the Russian/Israeli team tried to sell the same aircraft to China. The US arm-twisted Israel into foregoing the sale citing the danger of selling advanced radar tech to China.
US-built AWACS aircraft (E-3) or the equipment on them had nothing to do with this. These aircraft have never been sold to Israel though they have been sold to some NATO allies and to Saudi Arabia. The US had sold an earlier AEW aircraft, the E-2C, to Israel back in the 1980s.

The US gave gazillions of dollars worth of weapons to Afghan rebels when they were fighting Soviet troops. Many of the Afghans and their allied fighters became part of the Taliban or part of Al Queda, so yes we essentially gave our enemies gazillions of dollars minus X to our enemies.

There was a rather sad example of handing intelligence and supplies right into enemy hands in WWII, the Englandspiel, a German counter-intelligence operation in the Netherlands.

Basically the Germans captured an SOE operative and ordered him to radio back that everything was fine, send more equipment and agents please. The SOE man did, omitting security checks so HQ would know he was compromised. But the British sent more agents in regardless, leading to approximately 50 men being captured. The incompetence on display is so egregious that even now it’s debated whether or not it was intentionally, as a British double-bluff.

One could argue that Oliver North’s Iran Contra affair was an example of that, to the extent that it was unauthorized by US law at the time.

The claim at the time was that the weapons were doctored and would not work.

You are right. I confused the furor over the indigenous radar with the US complaints about the possible transfer of technology. Mea culpa.

Another instance of shipping by parcel, where the security breach was not on the part of the parcel’s sender but a failure of Cold War export shipping security checks:

On 22 October 1967 three KGB agents (a West German air force pilot among them) stole a AIM-9 Sidewinder air to air missile from an airbase in Bavaria and first drove across West Germany with it (as the missile protruded out of the car’s rear window they duly attached a red flag to it to comply to the German rules of the road).

After arrival in Krefeld they disassembled the missile, made a large parcel of the parts (except of the warhead’s fuse), addressed it to their KGB contact in Moscow and shipped it at the local post office. They did not expect that they had to fill in a short-form customs declaration to paste on the parcel, so not having planned what to do they wrote ‘Sidewinder’ in the description field. The parcel was duly shipped to Moscow.

Armin Faber landed his new FW190 fighter right at an RAF airfield after he was disoriented in a dogfight.

edit: Sorry, I just noticed that OP said “outside of a combat situation” so I don’t know if this would count and can not delete it.

The OP does specify hardware.

Plus, Manning and Snowden in leaking information, and presumably anyone else who leaked information to Assange, did so deliberately. The OP specifies unintentional transfers. But (if we overlook the point that information is not hardware) anybody who through carelessness makes military information accessible to an enemy agent, who duly acesses it, has unintentionally transferred the information to the enemy. And that, as you rightly point out, goes on all the time.

I suppose you could argue that, although Manning didn’t intentionally leak information to the enemy, whoever designed the systems that Manning operated created a situation in which Manning could and did transfer information to Assange, who published it, with the result that enemies could and presumably did acquire it. So that person - the designer of the system - unintentionally transferred information to the enemy, in a roundabout kind of way.

Any really hilarious incidents have probably been covered up, but are likely. Remember the big flap a couple years ago when a B-52 accidentally carried a couple of live nukes from South Dakota to Louisiana?

Speaking of nukes, the US kinda accidentally gave the Soviets a few examples of the first bomber that could deliver them in the '40s when they were technically allies, the reverse-engineering of which which really helped them out a few years later.

Some people say that military intelligence is an oxymoron!

From Wikipedia, AIM-9 Sidewinder:

During the Taiwan Strait battles of 1958, a Taiwanese AIM-9B hit a Chinese MiG-17 without exploding; the missile lodged in the airframe of the MiG and allowed the pilot to bring both plane and missile back to base. Soviet engineers later admitted that the captured Sidewinder served as a “university course” in missile design and substantially improved Soviet air-to-air capabilities. They were able to reverse-engineer a copy of the Sidewinder, which was manufactured as the Vympel K-13/R-3S missile, NATO reporting name AA-2 Atoll. There may have been a second source for the copied design: according to Ron Westrum in his book Sidewinder,[12] the Soviets obtained the plans for Sidewinder from a Swedish Air Force Colonel, Stig Wennerström. (According to Westrum, Soviet engineers copied the AIM-9 so closely that even the part numbers were duplicated, although this has not been confirmed from Soviet sources.)

Interesting aside:

The FP-45 Liberator handgun airdrops were intended to supply both WWII resistance fighters and end up in German hands at the same time. It was an example of giving the enemy weapons with the intention of conducting psychological warfare.

The Liberator’s net effect was considered minimal, and obviously the weapons themselves were of no use to the enemy to whom it was handed. But an interesting example of handing weapons to your enemy.