South Korea's Defense Minister Suh Wook said cross-border military tensions remain heightened amid North Korea's threats against the South's search for the remains of a fisheries official who was shot dead by the North last month.

During a parliamentary inspection of his ministry on Wednesday, Suh said Pyongyang has remained mum on Seoul's proposed joint investigation, despite apologizing for the incident and vowing to prevent a recurrence.

Several days following the September 22 incident, Pyongyang called on Seoul to stop intruding into its waters while conducting its search for the official. 

The South Korean military continues search operations south of the western de facto maritime border of the Northern Limit Line(NLL).

Assessing that the security situation on the Korean Peninsula is more complex and unpredictable than ever before, the minister vowed to maintain a readiness posture and ensure there is no vacuum in national security.