North Korean leader Kim Jong-un had flown to an eastern test site one day before his military fired off an unprecedented number of rockets from there, a military source said Friday, an indication that he may have had a direct hand in the Sunday night launch.

Kim visited the eastern city of Wonsan via a light aircraft, believed to be one of the Cessna models, last Saturday. The North fired off 25 ground-to-ground FROG-7 rockets into the sea the following night.

"It seems that Kim may have planned the rocket launch as the North Korea military fired off an unprecedented large number of rockets the following evening from Wonsan," the source said, asking not to be named.

With the joint military drills currently underway, the South Korean and U.S. forces have maintained a high level of vigilance because about 10 mobile launchers have been spotted at the same test site since the latest launch, in a potential sign of

additional provocations.

Kim's latest inspection illustrates the different leadership style from his late father Kim Jong-il, who had always used trains due to his fear of flying triggered by a 1976 helicopter crash that seriously injured him.

"Although Kim Jong-il had used trains for his provincial trips, Kim Jong-un has sometimes flown by a light airplane when visiting regions where there are airstrips," another source said, requesting anonymity. "It maybe be attributable to the young leader's more liberal nature."

The latest rocket launch came just two days after the North's National Defense Commission threatened to demonstrate its nuclear deterrence capability against the perceived U.S. hostility.

The communist state had fired Scud-C short-range missiles and artillery using multiple launcher systems with varying ranges between late February and early March, in an apparent protest against the joint military drills between Seoul and Washington.

The two-week war game Key Resolve ended on March 6, while the two-month combat field training Foal Eagle will run until April 18. (Yonhap)