A U.N. report says North Korea continues to smuggle nuclear arms and ballistic missiles via its embassies and overseas ghost companies.

Japan’s Kyodo News quoted a report by the U.N. Security Council Sanctions Committee as saying Monday that North Korea smuggled devices and materials related to nuclear weapons under the names of ghost companies. The document added that the communist state used its embassies and diplomatic missions to have such materials exempted from customs.

The report proposed that additional sanctions be imposed on individuals and companies that are suspected of being involved in such smuggling activities.

It also said that the North is capable of producing enriched uranium that could be used to create one or two nuclear weapons per year. The committee also raised the possibility that the North gathered technology on making nuclear weapons from advanced nations.