The national security advisors of the United States, South Korea and Japan on Saturday urged for a more robust international effort to curb North Korea’s advancements in nuclear weapons and missiles, as well as its military collaborations with other nations, citing concerns about potential arms transfers to Russia. The meeting in Seoul took place amid heightened tensions on the Korean Peninsula, marked by North Korean leader Kim Jong Un’s accelerated nuclear and missile program expansion and the endorsement of an escalatory nuclear doctrine allowing preemptive nuclear weapon use. The United States and its Asian allies have responded by increasing the...