Military authorities say they have not detected any particular movements from North Korea’s military following a statement by the powerful sister of the state's leader Kim Jong-un. 

Joint Chiefs of Staff spokesperson Colonel Kim Jun-rak said Monday in a briefing that no such unusual activity has been spotted, adding the South’s military is closely observing the North and maintaining a firm defense readiness posture. 

The remarks come in response to a question on whether the North’s military has shown any movement after Kim Yo-jong criticized South Korea in a statement on Sunday for failing to stop anti-Pyongyang leaflets from being sent by a defector group, warning of "corresponding action."

Some observers say Kim’s remark suggests that the North could seek to reinstall propaganda loudspeakers along the inter-Korean border. 

On June 21 of last year, North Korea reinstalled some 30 such loudspeakers near the border but removed them after just three days. 

On such a possibility, a South Korean military official said the military has detected no signs suggesting the North is aiming to reinstall the equipment.