The United States of America, the Republic of Korea, and Japan held a productive and substantive security meeting from April 16-17 in Washington, District of Columbia, to enhance trilateral defense cooperation in light of the evolving security environment in the region.... The officials reaffirmed that their governments will not accept North Korea as a nuclear-armed state, and agreed to closely coordinate to deter North Korean provocations.... In addition, the three countries held a productive discussion on cooperative measures for non-traditional security issues including humanitarian assistance and disaster relief, counter-piracy operations, and counter-ISIL efforts.[1]
Three years ago it was impossible to imagine the US and Iran co-operating about anything. Now the US has provided de facto aircover for Iranian operations against ISIS.