North Korea has allegedly been busy making 12 new nuclear weapons since the first summit between President Trump and Kim Jong Un in Singapore last June.

Experts from the US Defense Intelligence Agency came to that conclusion after analyzing satellite imagery that showed activity at the North’s nuclear sites had ramped up since the historic meeting, according to the Wall Street Journal.

Analysts believe North Korea could currently have as few as 20 and as many as 60 nuclear bombs, the paper reported.

The images appear to show trucks as well as people moving materials to and from the sites, including the Yongbyon Nuclear Scientific Research Center. Kim has previously expressed willingness to shut down the facility in part of a future deal.

The photos suggest that despite hopeful rhetoric from the two sides, the North continues to have no intention of surrendering its nuclear arsenal.

A second meeting between Trump and Kim in February ended in failure after the United States abruptly ended negotiations.

“We had a really productive time. We had some options. At this time, we decided not to do any of the options,” Trump said at a press conference explaining the decision. “Sometimes, you have to walk.”