Looks like Kim Jong Un isn't kidding. Three days after announcing that he would double the country's nuclear potential to prepare for war with the United States, he appeared at a facility to produce nuclear warheads for missiles. Pyongyang has publicly revealed for the first time that it has a uranium enrichment facility, South Korea's Yonhap news agency reported.

State media reports of Kim's visit to the Nuclear Weapons Institute and nuclear weapons materials production facility were accompanied by the first photographs that provided a rare glimpse of North Korea's nuclear program, which has been banned by multiple United Nations resolutions. They show Kim walking between long rows of metal centrifuges, devices for enriching uranium.

In the report, the state agency did not clearly state when the visit took place or where the facility was located. Kim urged workers to produce more material for tactical nuclear weapons, saying the country's nuclear arsenal was vital to countering threats from the United States and its allies: "Self-defense weapons and pre-emptive strike capability are needed," he said. The North Korean leader who oversaw the test firing of a new 600 mm rocket launcher.

Hong Min, a senior analyst at the Korea Institute for National Unification in Seoul, believes these photos could be a message to the US ahead of November's presidential election.

"In this way, Kim wants to show the next administration that it will be impossible to denuclearize North Korea. It is also a message asking other countries to recognize North Korea as a nuclear state," Hong told AFP.

A senior official from the South Korean president's office said South Korean and US intelligence services were monitoring the North's behavior, "taking into account all possibilities." As "Koreja JungAng Daily" writes, the Government in Seoul estimates that North Korea has completed preparations for the seventh nuclear test. Some security experts speculate that Pyongyang is likely to conduct another atomic test before the US presidential election.

Security experts assume that North Korea has several uranium enrichment sites. Analysts say commercial satellite images have shown construction in recent years at the main nuclear science research center in Yongbyon, including its uranium enrichment facility, suggesting possible expansion, Reuters reports.

Uranium is a naturally occurring radioactive element. To produce nuclear fuel, raw uranium undergoes processes that result in material with an increased concentration of the uranium-235 isotope. The head of the International Atomic Energy Agency, Rafael Grossi, said on Monday that the UN nuclear watchdog had detected activity consistent with the operation of a reactor and a suspected enrichment facility at the Yongbyon centrifuge.

The new type of centrifuge shows that North Korea is improving its fuel cycle manufacturing capabilities, said Ankit Panda of the US Carnegie Endowment for International Peace.

"Kim also seems to be suggesting that North Korea's tactical nuclear weapons projects could primarily rely on the use of uranium as the primary core material," this expert noted.

In 2010, North Korea invited some foreign scientists to tour the Yongbyon centrifuge facility, but Jenny Town of the US Stimson Center says these are the only photos of the uranium processing equipment so far. North Korea has previously shown photos of what it says are nuclear warheads.

Estimates of the number of North Korean nuclear weapons vary widely. In July, a report by the Federation of American Scientists concluded that the country may have produced enough fissile material to make up to 90 nuclear warheads, but that it likely has amassed close to 50.