The U.S. moved to again cripple North Korean access to a bank (Kwangson Banking Corporation) that has been facilitating illegal North Korea activities. This sort of things makes the North Koreans very unhappy. Three years ago, the U.S. discovered that shutting down North Korean access to a money laundering bank in Macao, China, apparently did more damage than previously thought. The North Koreans had long engaged in drug smuggling, counterfeiting and money laundering to provide foreign currency for foreign imports. Some of these imports were for weapons programs, but there were also a lot of consumer goodies to keep the few thousand key leaders in the communist police state happy. Take away the toys, and the protectors of the state get angry and restless. North Korea got so angry about losing access to this Macao bank, that the U.S. had to ease up before North Korea would even deign to resume talking (about their nuclear weapons and ICBM programs).
As a result, North Korea got $25 million in profits from criminal activities, which were frozen in the Macao, China bank, freed and moved to a Russian bank. But North Korea has not got access to the international banking system restored, and the North Koreans are not happy with this. Drug dealing and counterfeit currency are major earners for the North Koreans, and without access to the international banking system, expenses are higher.