Approximately two months since President Trump and North Korean leader Kim Jong Un met in Singapore, nuclear diplomacy between Washington and Pyongyang is deadlocked — and it could be approaching a breaking point.

Trump’s postponement of Secretary of State Mike Pompeo’s visit to Pyongyang last week was the tip of the iceberg in terms of the frustration building on both sides of the negotiating table. The administration is no longer as starry-eyed about Kim’s apparent commitment to denuclearize, notwithstanding the president’s once unrestricted optimism. The North Koreans are frustrated by Washington’s resistance to discussing other items in the Singapore statement, including the signing of a peace treaty formally ending the Korean War.