North Korean leader Kim Jong-un has not only confirmed that his country possesses a nuclear arsenal, he’s also alluded to secret facilities where they are stored, according to a report in Korea JoonAng Daily.

The South Korean newspaper says it’s obtained a confidential document from a government arm called the North Korean Workers’ Party Munitions Industry Department. The document was reportedly drawn up after Kim made an unpublicized visit to a secret facility called “Factory 92” on February 25 — 12 days after Kim’s half-brother, Jim Jong-nam, was assassinated in Malaysia.

South Korean military sources believe that nuclear warheads and missiles are produced at the factory.

“Development, production, storage and management of nuclear weapons are the most important of our country’s military secrets,” Kim was quoted as saying in the report during his inspection of the factory. “They are the ultimate secrets that decide our country’s fate.”

A South Korean military official was quoted as saying that the North has about 30 facilities scattered throughout the country to make components related to nuclear bombs and missiles.