Taking advantage of a perceived thaw in relations between Tokyo and Seoul, U.S. President Barack Obama met with his counterparts from Japan and South Korea on the fringes of the Nuclear Security Summit to promote greater trilateral unity to address North Korea's nuclear ambitions.
But at their meeting in Washington, the leaders of the three nations came up short on ideas about how to persuade Pyongyang to stop provocative acts like nuclear weapons tests and rocket launches.
"The United States has invested quite a bit of time and diplomatic energy," White House spokesman Josh Earnest told reporters in referring to President Barack Obama's efforts to help his Japanese and South Korean counterparts mend fences.