This is one of those shadowy war mysteries with a backstory that belongs in a Robert Ludlum novel. We’ll never know the true inside story. But it’s interesting nonetheless.

You may recall back in 2011 as Barack Obama was heading out of the White House one day to take his mother-in-law along on a South American tour, he dropped the news that oh, by the way, he’d ordered U.S. air forces to help European allies oust Libyan strongman Moammar Gadhafi.

He launched this multi-month offensive without congressional approval.

Gadhafi’s crime (actually, it hadn’t happened yet) was he threatened to shoot civilians if some rebels did not stop fighting. Obama’s proclaimed cover story was a civilized world could not abide such potential threatened violence.

Obama’s professed concern for innocent civilians went poof! soon after, as more than 400,000 Syrian civilians were actually killed by government and Russian bombs, guns and chemical weapons ruthlessly putting down a civil war there.

Remember Obama’s red line over Syria’s chemical weapons? He threatened military action, but then declared he couldn’t really do such a thing without the congressional approval he didn’t care about in 2011.

The irony, of course, is that Obama was a Nobel Peace Prize winner. Take that Oslo! And the very same allies including the U.S. had promised a few years earlier to leave Gadhafi alone if only he’d end his nuclear weapons program and hand over the goods.

Gadhafi had a great hat collection, but he was not a nice man. However, he did indeed surrender his entire weapons of mass destruction program. His reward, in late 2011, was to be dragged from a culvert, beaten and executed by a mob. Secy. of State Hillary Clinton was caught on tape exulting over the death.

This is the kind of Western diplomatic duplicity that sticks in the minds of would-be nuclear powers like North Korea and Iran when U.S. officials sincerely ask them to relinquish their weapons programs.

Anyway, Libya has been a failed state ever since. Militias roam the land. Remember the murder of four Americans in Benghazi that Obama vowed to avenge? ISIS and al Qaeda trainers teach new jihadis there.

The U.S. and United Nations recognize the weak government in Tripoli. But it faces rebel challenges, most seriously from a general named Khalifa Hifter. In a surprise raid last week government troops took a rebel compound south of Tripoli. And there they found a large arms cache including a batch of U.S. anti-tank missiles worth more than $600,000.

The American Javelin missiles (see above) were packed in Raytheon/Lockheed Martin crates from a 2008 shipment to the United Arab Emirates, which is supposed to be a US ally. Passing on US weapons is also supposed to be illegal.

A State Department spokesman harumphed: “We expect all recipients of U.S. origin defense equipment to abide by their end-use obligations.”

Turns out, weapons from China and elsewhere are also showing up on all sides in Libya, as various countries pick their favorite militia to fight proxy wars.

All part of the unintended consequences of ousting a bad guy with no viable plan for his replacement. Oh, wait! Didn’t the U.S. also do that in Iraq to Saddam Hussein?