Japanese Defense Minister Itsunori Onodera says the latest political development in North Korea needs to be closely monitored.
He told reporters on Friday that Japan should carefully analyze the factors behind Jang Song Thaek's execution.
He added that if it suggests the military's growing political influence, Japan needs to observe events closely.
Onodera cited as sources of concern North Korea's missile tests, which it has vowed to continue, as well as its nuclear experiments.
Dec. 13, 2013 - Updated 04:01 UTC