It will now be easier for buyers in foreign conflict zones to obtain firearms made in the US, including high-capacity semi-automatic rifles like the AR-15, short-barrel shotguns, and “.50 caliber rifles” capable of firing bullets .5 inches in diameter, under a new rule enacted by US president Donald Trump.

When a US company wants to export a weapon, it typically must receive approval from the US Department of State, which monitors the official US Munitions List and determines if selling deadly technology overseas is in the interest of national security.

Now, many firearms formerly classified as “close assault weapons and combat shotguns” will be monitored by the Department of Commerce, which puts fewer restrictions on trade and need not notify Congress of weapons purchases. Gun manufacturers have pushed for the reclassification for years. Fully automatic weapons are still under State’s purview.

The move reflects a domestic debate about the sale of semi-automatic rifles, which are frequently used in mass shootings, in American retail stores. Gun safety advocates call them “weapons of war” (their designs are based on the fully-automatic weapons used by US soldiers), but the Trump administration is explicitly saying that these are not military weapons.

Experts, however, disagree. Most conflict deaths are caused by small arms, which tend to last longer and spread further than other weapons. Throughout the Middle East, US forces frequently face off against extremist groups armed with American firearms that had previously been given to ostensibly friendly regimes.

“The big ticket weapons get a lot of the public attention—the fighter jets and the tanks and the anti-missile systems—partly because of the dollar values attached to them,” Jeff Abramson, a senior fellow at the Association for Arms Control, told Quartz. “The reality is that it is the smaller weapons that fuel and extend conflicts around the world. … We might sell them now to our ally of the day, but down the road we see them misused in that conflict or in other conflicts.”

In 2016, the US blocked the sale of 26,000 semi-automatic rifles to the Philippines because diplomats and lawmakers were concerned that they would be used by police there in a violent anti-drug campaign characterized by thousands of extra-judicial killings.

Under the new rules, Congress would not need to be notified of such a sale, and the lead decision maker would not be the human-rights focused State Department, but business-focused Commerce.

Tom Malinowski, who was assistant secretary of state when the Philippines sale was blocked, is now a member of Congress from New Jersey.

“I can 100 percent guarantee to you that if the Commerce Department had the final say in that sale they would not have made the same decision because the Commerce Department’s ethos, mandate, and mission was to support American manufacturers in their efforts to export their products,” Malinowski said at a hearing on the rule in 2019. “That is exactly why the Commerce Department exists. The State Department exists to raise foreign policy, human rights, and national security considerations.”

It’s hard to say how many more guns will be sold abroad by US manufacturers under the new rule or where, but arms control experts worry about more firearms fueling conflicts everywhere from sub-Saharan Africa to central America. Already, drug violence in Mexico is fueled by legal gun purchases across the border in the US.

Still, the rule may not stand for long. A group of 21 state attorneys general, led by Washington attorney general Bob Ferguson, is challenging the rule in court because it also takes 3D printed firearms off the US Munitions List.

Entrepreneurs seeking to sell or share designs online for 3D printed guns—which can be difficult to trace and evade conventional metal-detecting security systems—have been blocked by US export rules, since posting such information on the internet is effectively exporting it. By removing 3D printed weapons from the list, they will be able to proliferate more widely in the US.

The 2020 election, too, may result in the rule being reversed—every major Democratic candidate supports an assault weapons ban already, and two—former vice president Joe Biden and senator Elizabeth Warren—have explicitly come out against this decision.