“It’s a move stemming from confidence after completing his nuclear weapons program — he’s seeking a deal,” a senior former North Korean official who defected to the South tells TIME. “He looks a lot more wild than his father or grandfather [former regime leaders Kim Il Sung and Kim Jong Il], but I have seen him grow as a politician since his inauguration. I’ve seen him grow as a strategic thinker.”

But a visit by Kim to Beijing first injects a new element of uncertainty. China is key to sanctions enforcement, given that 90% of North Korean trade passes over the same shared frontier where photos Monday evening showed that 21-carriage train trundling past the Chinese border city of Dandong. (The train appeared very similar to one that Kim’s father, Kim Jong Il, took to Beijing in 2011 and the younger Kim reportedly has a fear of flying.)

Owing to pressure from Trump, Beijing has been enforcing the sanctions comparatively strictly, slashing imports of North Korea coal and labor that form the regime’s main cash cow. But Beijing and Washington are only loosely aligned, and over the decades the Kim dynasty has been deft at exploiting the cracks between adversaries to further its goals.