North Korea released first-ever photos of a uranium enrichment site on Thursday.

Supreme leader Kim Jong Un  has been known to show off his nuclear bombs, but this week he revealed the facilities that create the key material that powers them. 

Kim released photos of himself touring the facility as he called for his military to ‘exponentially’ increase its nuclear arsenal and be ready for combat with the U.S. and its allies. 

The pictures released by state media KCNA show a glimpse into the country’s secretive nuclear program, which is banned under multiple UN Security Council resolutions. 

The images show Kim walking through rows of centrifuge machines that spin uranium at high speeds to produce nuclear warheads. 

Kim visited the Nuclear Weapons Institute and a production base for weapon-grade nuclear materials, KCNA said, and instructed the base to ramp up the number of centrifuges ‘in order to exponentially increase the number of nuclear weapons.’

‘He went round the control room of the uranium enrichment base to learn about the overall operation of the production lines,’ KCNA said, and was pleased to see the base ‘dynamically producing nuclear materials.’

The world gets little opportunity to glimpse life in the reclusive, nuclear-armed state, but photos also showed Kim visiting an army training base on Wednesday to ‘guide the drill of combatants,’ KCNA said/

On Thursday, North Korea fired multiple short-range ballistic missiles toward the sea, which landed in the waters between the Korean peninsula and Japan. The distance of the missiles suggests that they were designed to attack South Korea.

It was North Korea’s first public weapons firing activity in over two months. 

Kim said that his pledge to double down on his nuclear efforts was because North Korea faces ‘a grave threat’ because of what he called ‘the reckless expansion’ of a U.S.-led regional military bloc.

Last week North Korea flew balloons full of trash toward South Korea for five straight days. 

Officials in Seoul slammed Pyongyang for its nuclear developments.

‘Any nuclear threat or provocation by North Korea will be met with an overwhelming and strong response from our government and military, based on the solid extended deterrence of the South Korea-US alliance,’ the Ministry of Unification was quoted as saying by South Korea’s Yonhap news agency.

It’s not clear how many nuclear warheads North Korea possesses. In July, a report by the Federation of American Scientists concluded that the country may have produced enough fissile material to build up to 90 nuclear warheads, but that it has likely assembled closer to 50.