The South Korean military has detected signs that North Korea could be preparing for short- and mid-range missile launches.

A military official said Friday that mobile launchers loaded with Scud and Rodong missiles were identified by joint South Korea-U.S. reconnaissance assets. 

The South's military is believed to have picked up signs that the North may launch a Scud missile near Wonsan and a Rodong missile in North Pyongan Province. 

A Scud has a range of under 500 kilometers and a Rodong missile can go as long as 12-hundred kilometers.

The military official said that Pyongyang is likely to strategically weigh the timing of the launches and that Seoul is closely monitoring movements on the North's missile bases. 

After firing artillery shells across the Demilitarized Zone toward South Korea on Thursday, the North declared a "quasi-state of war."