A domestic institute says that North Korea is believed to have secured a technology to miniaturize nuclear warheads and load them onto its Scud and Nodong ballistic missiles.

The Institute for National Security Strategy under the National Intelligence Service on Sunday presented the assessment in its 2016 annual report.

The institute expected that Pyongyang will drastically increase the number of its nuclear warheads and develop an intercontinental ballistic missile capable of reaching the United States mainland by 2020 at the latest.

The report said that the seriousness of the North Korean nuclear program lies in the rapid increase in the number of warheads, as well as its miniaturization and diversification.

It added that the North is estimated to have succeeded in developing nuclear warheads comparable to “boosted fission weapons” through its fourth and fifth nuclear tests.