Pakistani truckers who carry NATO supplies to landlocked Afghanistan are on strike over a new government-imposed system, potentially disrupting an important lifeline for international troops there.

The All Pakistan Goods Transportation Association has unofficially blockaded 4,000 vehicles carrying nonlethal supplies through the supply route in protest over lower wages, inadequate security and corrupt officials, says Jehanzeb Khan, head of the transport workers union.

Under the new system, truckers are required to go through authorized companies to carry NATO supplies instead of making individual deals with lower pay.

Khan also said truckers were not provided adequate protection from Taliban attacks and accused security officials of askin $165 in bribes to pass through to the northwest Torkham border. Supplies continued through the other crossing, Chaman, in southwestern Pakistan, according to AFP.

The union said they would not resume operations until the system is scrapped, Reuters reports.

“We will continue striking as long as our demands aren’t met,” transporter Abdul Ghafaaz Niazi said. “Custom collectorate officials are corrupt. We won’t listen to them. If they want to lose billions of rupees every day, they can.”

A spokesman for Afghanistan’s NATO-led force declined to comment on how the strike might affect supplies.