Thursday’s summit between Prime Minister Fumio Kishida and South Korean President Yoon Suk-yeol underlined the thawing bilateral ties, with the two leaders agreeing to resume “shuttle diplomacy,” dining at Yoon’s favorite omurice restaurant in Tokyo’s glitzy Ginza district and drinking beer and Korean soju with their ties off.

But beyond the good food and drinks, what really prompted the two leaders to improve frosty bilateral ties was a deteriorating security environment due to North Korea’s repeated missile launches and the need for the two countries to cooperate over economic security to ensure a stable semiconductor supply chain.

“In response to North Korea, which is further advancing its nuclear and missile activities ... we confirmed the importance of strengthening the deterrence and response capabilities of the Japan-U.S, and South Korea-U.S. alliances and vigorously promoting security cooperation among the three countries,” Kishida said during a joint news conference.