Relations between the two Koreas have been strained in recent years , with provocative actions taken under the rule of Kim Jong-il ( such as the suspected torpedoing of the ROKS Cheonan and the bombardment of Yeonpyeong Island ) and his son , Kim Jong-un ( such as the rocket launches in April and December of 2012 and North Korea 's third nuclear test ) . Kim Jong-un 's sudden accession and limited experience governing have also stoked fears about power struggles among different factions leading to future instability on the Korean Peninsula
North Korea 's third nuclear test
2013 North Korean nuclear test
Korean reunification