Every time an insurgency threatens U.S. interests in the Middle East, a familiar question always seems to follow: Where do they get their Toyota pickup trucks?

Since the mid-1970s, from Saharan Africa to Central Asia, “technicals” — light pickup trucks with heavy weaponry mounted in the bed — have been a game-changer for irregular forces. And just as insurgents display a consistent preference for Russian AK-type assault rifles, their brand of choice for technicals is the similarly-rugged Toyota Hilux pickup. With Islamic State becoming the latest group to display an affinity for the Hilux, U.S. officials want to know: Why do terrorists love Toyotas, and how are they getting them?

The former question is considerably easier to answer than the latter: Hiluxes are among the most rugged and reliable vehicles on the global market. Tougher and more off-road oriented than the related Tacoma sold in the US, the Hilux is as popular with humanitarian groups and businesses operating in rugged corners of the world as with terrorist groups.

Though other carmakers sell competing models — Nissan Navara, Suzuki Equator, Ford Ranger, Chevrolet Colorado — none has the same name-brand recognition for bulletproof reliability. An infamous episode of BBC”s “Top Gear,” the world”s most- watched car program, once demonstrated the truck”s legendary toughness by unsuccessfully attempting to destroy it in spectacular fashion, flooding it in an ocean tide and placing it atop a condemned building that was blown up.

The use of Toyota pickup technicals was pioneered by the Sahrawi People”s Liberation Army in their conflict with Morocco and Mauritania in the 1970s. In the 1980s, a similar conflict between Libya and Chad s such heavy use of the trucks that it became known as the “Toyota War.” From the civil wars in Somalia to the Taliban”s Hilux-based blitzkrieg in Afghanistan, the 1990s cemented the Toyota pickup”s role as an icon of a new generation of insurgents.

Such are the Hilux”s charms that even American and allied special forces have used them in conflicts, which has led to more than a few strange passes. After the 2001 invasion of Afghanistan, Taliban fighters were found with maple leaf tattoos: a tribute, it turned out, to a stolen shipment of Hilux pickups from the Canadian government. A more recent set of 43 Hiluxes, sent as nonlethal aid to Syrian rebels, now seems to have fallen into the hands of Islamic State. It”s not just Toyotas: A Ford F-250 that was traded in by a Texas plumber ended up in Syria, shown transporting ISIS members in a propaganda video with his plumbing business phone number still advertised on the truck”s side.

Toyota”s response to the latest round of inquiry, from Iraqi officials as well as American, is the same as always: Insist it has a policy not to sell vehicles to potential paramilitary buyers, and explain its supply-chain safeguards to curious officials. “We briefed Treasury on Toyota”s supply chains in the Middle East and the procedures that Toyota has in place to protect supply-chain integrity,” Toyota”s Ed Lewis told ABC News. In the past, however, Toyota had been less guarded about the issue, with one spokesman telling the NY Times in 2001: “It is not our proudest product placement, but it shows that the Taliban are looking for the same qualities as any truck buyer: durability and reliability.”

Decades of questions about Toyota”s role in these sales have failed to turn up any evidence of the firm”s involvement. Islamic State”s trucks appear to have been stolen from American- backed Syrian rebels and the Iraqi army itself, as well as off the streets in the U.S. and elsewhere. In Australia, where the Hilux is a best-selling pickup, thefts of the vehicles have been rising, raising suspicions that they are being shipped to Syria and Iran through organized crime channels.

With no evidence that Toyota is actively trying to sell trucks to terror groups, any U.S. or Iraqi investigation will probably be a waste of time. And as long as pickups aren”t controlled as military goods, keeping Hiluxes out of the hands of America”s enemies will be all but impossible. If the fighters who most need rugged reliability from their pickups choose Hiluxes, well, that”s more of a matter of concern for Toyota”s competitors than the government.