During last month's inter-Korea summit, South Korean President Moon Jae In gave North Korean leader Kim Jong Un a huge welcome, with an inspection of the honour guards and a sumptuous official dinner.
But the warm welcome was not Mr Kim's only gift from the South's leader; he also received a USB drive from Mr Moon.
According to various South Korean media outlets quoted by Business Insider, the USB drive contained an e-book and presentation on the "New Economic Map of the Korean Peninsula" which Mr Moon announced last year.
Business Insider also reported that the map is a blueprint for how economic cooperation between the two Koreas could work and includes three "belts" - one along the east coast and Russia for energy and resources, another along the west coast for transportation and logistics, and a third across the land border for tourism.
The map was said to be an added incentive for Mr Kim to abide by the declarations made at Panmunjom, where the two leaders announced that the two Koreas would end the Korean War, normalise ties and denuclearise.
Korea JoongAng Daily quoted South Korea's Unification Ministry, which mentioned that the USB also contained "information related to a power plant".
"The USB makes the case to Kim - there really is another path for you," John Delury, an expert in North Korean affairs at Seoul's Yonsei University, told Axios.
He said the USB, which contained a plan for tens of billions worth of economic development in North Korea including railways and energy, sent the message to Kim: "We're serious about working with you for what we think is your real ambition - to be a wealthy East Asian country."