South Korean navy Captain Choi Won-il was commanding the corvette ROKS Cheonan on a routine patrol in the Yellow Sea when a North Korean torpedo struck, splitting the vessel in two.

The attack on March 26, 2010 killed 46 sailors, making it one of the deadliest incidents between the two Koreas since the Korean War.

Choi, now head of the Patriots and Veterans Research Institute, sat down with NK News ahead of the 15th anniversary of the tragedy to reflect on his experience of the sinking, what led to it and its lasting impact on the South Korean military.