The high price of tobacco in Gaza has given rise to a cigarette smuggling industry that now threatens United Nations aid convoys, according to a new report from the Wall Street Journal.

Cigarettes can cost as much as $25 each in the war-torn region, and gangs have found ways to smuggle them in as contraband alongside aid deliveries. One group of Palestinian men demanded entry to a U.N. warehouse last week to secure a stash of cigarettes they knew was inside, according to the Journal.

The smuggling operation only enhances the dangers for aid convoys operating in Gaza, which have already faced mobs of Palestinians stopping them in their tracks.

Demand for cigarettes skyrocketed in early May when Israeli forces seized control of the Rafah crossing between Gaza and Egypt. They closed the border to virtually all trade, cutting off a previously steady flow of tobacco products into Gaza.

Opportunists then began smuggling the product into the region via the aid packages coming in to United Nations facilities from all over the world.

The danger has contributed to aid groups’ refusal to make deliveries beyond the Gaza border. Over 1,000 truckloads worth of aid are still sitting just within Gazan territory at the Kerem Shalom crossing with Israel, according to the Journal.

‘This is threatening to undermine everything we’re trying to do,’ a U.N. official told the outlet.

President Biden’s administration sought to facilitate aid delivery by constructing a temporary pier on the Gaza coast last month. The effort soon met disaster, however, as weather rendered it unusable in a matter of days.

The U.N. also announced on June 10 that it would halt food distribution at the pier due to security concerns. The U.S. spent roughly $320 million on building the structure.

Rocket attacks struck two warehouses holding aid delivered to the pier in early June, contributing to the pause in delivery. The Biden administration has said it is committed to the maintenance of the pier moving forward.