It’s tough to prosecute a powerful and well-known super-criminal like Joaquin “El Chapo” Guzman when you’ve been in bed with him.

That’s a lesson the US is learning the hard way. The renowned Sinaloa cartel leader is currently on trial in Brooklyn, New York and a lot has come to light since his hearings began several weeks ago; from horror stories of mass murders, to ingenious jalapeno coke smuggling schemes.

Undoubtedly, there is a lot for the prosecution to work with.

But there is one topic that the prosecution doesn’t want the jury to hear about. A topic so damning that they’ve asked the judge to make any and all questions relating to it “completely off limits.” A topic that distinctly illustrates how entangled our two-faced federal government is with the drug cartels they claim to be fighting.

It was called “Operation Fast and Furious” and it was a botched gun running sting, initiated by the Bureau of Alcohol, Tobacco and Firearms (ATF). The operation ended up arming El Chapo’s Sinaloa cartel with over 2000 military grade firearms, almost none of which were ever recovered.

Operation Fast and Furious ran from 2009 to 2011, and according to the ATF it was intended to weaken the Mexican drug cartels by identifying the routes by which they smuggled weapons into Mexico.

Here was the gist of the plan: use straw man vendors to sell a shit load of American guns to known cartel middlemen. The ATF, in cooperation with the FBI and DEA, would then monitor the “pipelines” that the guns moved through. They’d follow them straight to the cartels and bring down the pipelines that got them there, instead of just the small potato traffickers at the bottom.

It was a risky plan. One that didn’t go so well.

The feds lost track of the 2000 firearms almost instantly. They watched them vanish into the pipelines they had hoped to expose, directly arming the Sinaloa cartel with weapons that would soon be used against them.

Which didn’t take long.

In 2010 a Customs and Border Patrol Agent named Brian Terry was shot and killed in a shootout. Two of the weapons found at the scene were traced directly back to Fast and Furious. Then again in 2011, ICE agent Jaime Zapata was gunned down by cartel members. And the murder weapons? Yeah, you guessed it. They’d been supplied by our government.

As of 2013 the US State Department reported that Operation Fast and Furious had only managed to track down 105 of the 2000 weapons they sold to the cartel. An additional 462 have been discovered by police on both sides of the border, often at the scenes of ugly and violent crimes.

Roughly 1,400 Fast and Furious firearms remain unaccounted for.

In fact, one of these guns was even discovered at El Chapo’s personal safe-house shortly before his arrest. A Barrett .50 caliber recoil-operated, semi-automatic anti-materiel sniper system powerful enough to blast through rail cars and destroy commercial aircraft and helicopters…

“Those guns are going to be recovered for the next 20 years,” ATF special agent Tom Mangan told Vice News. “But some of them we'll never find, because they may never get traced by law enforcement in this country, or — given that so many ended up in Mexico — whether those departments will ever even trace those guns.”

Clearly this operation went badly wrong. It is an embarrassment how it all played out and a tragedy that guns our government sold to bloodthirsty criminals are now being used to kill people. It is not great PR for the Feds.

Nor is it something that the prosecutors of El Chapo want his jury to hear about.

Operation Fast and Furious has been brought up several times in the weeks since El Chapo’s trial began, and every time it has, it’s raised frantic objections from the prosecutors. They say that any information related to the operation will only “distract and confuse the jury,” and requested that all mentions of it be banned outright.

They know what a humiliating failure Operation Fast and Furious truly was. They know they armed dangerous criminals, and they know those arms came back to take American lives; that those arms are still out there being used against Mexican police officers, border patrol agents, and innocent civilians.

And they don’t want people to fixate on that — which is exactly why we should.

Because, here’s the thing: the US has a bad track record of arming dangerous groups, on purpose, with the hope that they’ll do our dirty work for us. It’s how we created Saddam Hussein. It’s how we created Al Qaeda and it’s how we created ISIS. The DEA had already been striking deals with El Chapo, giving him “carte blanche” to smuggle drugs into the US in exchange for information they could use against his rivals — Los Zetas and the Juarez and Tijuana Cartels.

Who’s to say this “accidental” loss of firearms wasn’t actually intentional? What if the Feds never had any intention of tracing those guns in the first place?

It wouldn’t be the first time America tried something like that, and it came back to bite us in the ass.

Either way, though, Operation Fast and Furious doesn’t look good for the Feds: if it was intentional, then we knowingly armed dangerous drug gangs with weapons we knew they’d use against us.

If it was accidental, then our government might just be dumber than we give them credit for.