PYONGYANG, March 24  -- The top leader of the Democratic People's Republic of Korea (DPRK) Kim Jong Unhas guided a ground test for heavy-lift, solid-fuel rocket engine and its separation, the country's official news agency KCNA reported Thursday.

The test was aimed at testing the structural safety and the thrust of the newly developed rocket engine and gauging the working specification of heat separation system, said KCNA.

The test proved successful. The top leader, who was satisfied with the result, said this test helped boost the power of ballistic rockets and guaranteed achievement of goals for national defense science and technology this year.

Kim emphasized that the test of the newly designed rocket engine and its separation is "of historical and strategic importance" as the engine is a product of self-reliance and self-development.

On Monday, Kim guided a test firing of new-type, large-caliber multiple rocket launcher, the second time he has watched the test firing of the newly developed rocket launching system in a month.

On March 3, Kim ordered the military to get nuclear warheads ready for use when needed at any time when he guided the test firing of the new-type rocket launcher for the first time.

On March 10, the DPRK's top leader told all nuclear strike means of the strategic force to be ready for action when he watched a firing drill of ballistic rockets, which the Republic of Korea said were two short-range Scud missiles.

These moves by Pyongyang came amid escalated tensions on the Korean Peninsula after South Koreaand the United Statesstarted their joint annual war games "Key Resolve" and "Foal Eagle" on March 7. The Key Resolve drill ended Friday, but the Foal Eagle field training exercise would last until April 30.

Pyongyang has repeatedly condemned and called for suspension of the joint military exercises, claiming they are "war rehearsals for northward invasion."