WASHINGTON,  (UPI) — North Korea continues to import components from China that could go toward nuclear weapons development, an analyst said Tuesday.

David Albright of the Institute for Science and International Security told reporters at a Johns Hopkins University seminar that the parts being imported into North Korea from China haven’t been curtailed, South Korean newspaper Hankook Ilbo reported.

Pyongyang is transporting aluminum tubes, vacuum pumps, valves, cylinders of uranium hexafluoride and a variety of materials despite sanctions, according to the analyst.

Computer numerical control equipment, or CNC, are being procured from Siemens Taiwan, which reduces costs, Albright said.

The analyst also said key products and technologies that could go toward the assembly and operation of a gas centrifuge cannot be manufactured in North Korea, and they must be sourced from abroad.

North Korean officials are buying the equipment from intermediary firms in Hong Kong and mainland China. This way, they are able to circumvent embargoes.

The brokers purchase equipment in China, including Japan-made products, on behalf of Pyongyang’s enterprises, and they are then able to transport the goods across the China-North Korea border, Albright said.

Customs is easy to get through, although Beijing agreed to implement North Korean sanctions in March at the United Nations Security Council.

China has not been as cooperative as it could be with regard to enforcing the law and penalties, Albright said.

Other data have raised questions regarding China’s effective implementation of international sanctions.

Trade appears to be growing despite new bans.

Huang Songping, a spokesman for China’s General Administration of Customs, announced in April total trade with North Korea worked out to $491.8 million in March, up 20 percent from March 2015.

Beijing’s customs agency, however, had said the enforcement of North Korea trade embargoes would not go into effect until April.