Within hours of North Korea's January 6 nuclear test, President Park Geun-hye of South Korea picked up the phone and called President Barack Obama in the White House and Japanese Prime Minister Shinzo Abe in Tokyo to discuss a joint response to Pyongyang's latest nuclear gambit. Both leaders gave President Park unequivocal and resolute support for taking retaliatory action. Meanwhile, defense ministers and top foreign affairs officials of the three nations also held urgent telephone conferences to coordinate responses.