Leaked documents have revealed that Chinese tech giant Hauwei helped the North Korean government build and maintain the country’s commercial wireless network.

The internal documents were obtained by the Washington post from a former Huawei employee who considered the information to be in the public’s interest.

The revelations call into question about whether Huawei violated US export controls to furnish equipment in North Korea, where the regime has faced intensive international sanctions over its human rights abuses and nuclear weapons program.