North Korea has replaced its hawkish armed forces minister after just six months in the job -- the latest in a long line of top military reshuffles by supreme leader Kim Jong-Un.

The new minister was identified by the Korean Central News Agency on Sunday as Jang Jong-Nam, a relatively young and little-known field commander believed to be in his mid-50s.

He replaces Kim Kyok-Sik, whose appointment in November last year was seen as a hardline choice given that he was widely believed to have directed -- as commander of the 4th Army Corps -- the 2010 shelling of a South Korean border island.

The People's Armed Forces Ministry is essentially the defence ministry and comes under the control of the powerful National Defence Commission.

Kim Jong-Un has substantially reshuffled his military top brass in an apparent attempt to secure his leadership since taking over the reins of power from his late father in December 2011.

Kim Kyok-Sik's replacement comes as the Korean peninsula is emerging from a period of highly-elevated military tensions that followed the North's nuclear test in February.

South Korea noted the personnel change and said Monday it was closely monitoring all internal shifts in the North's military.

"We do not know if (Jang) is a less hawkish figure, but it appears that he is from a younger generation," said defence ministry spokesman Kim Min-Seok.

"Just because there is a new dot that does not mean that a whole line or landscape changes. We need more time to figure out the overall direction," Kim added.

Prior to his appointment, Jang was reported to be the commander of the Korean People's Army's 1st Corps in Kangwon Province on the east coast. A recent photo in the ruling party's Rodong Sinmun newspaper showed him as a three-star general.

US carrier joins S. Korea drill despite North anger
Seoul (AFP) May 13, 2013 - South Korea and a US strike force led by the nuclear-powered aircraft carrier USS Nimitz kicked off Monday a joint naval drill slammed by North Korea as a "wanton" provocation and rehearsal for war.

The two-day exercise began with the departure of the 97,000-tonne Nimitz, one of the world's largest warships, from the southern South Korean port of Busan where it had been docked over the weekend, the US navy said in a statement.

"The operations include integrated flight operations, air defense events, surface warfare training events, precision ship maneuvers, and liaison officer exchanges," it said.

A number of other naval ships including guided-missile cruisers and a guided-missile destroyer will also take part in the drill designed to "reinforce regional security and stability", it added.

The exercise comes as the Korean peninsula is only just emerging from a period of highly elevated military tensions triggered by North Korea's nuclear test in February.

Angered by UN sanctions imposed after the test and by a series of large South Korean-US military drills, Pyongyang spent much of March and April issuing dire warnings including threats of nuclear strikes against Seoul and Washington.

The North called the latest exercise with the Nimitz "a grave military provocation" that would trigger a fresh cycle of escalating tensions.

"This is a wanton threat against us... that will push the peninsula to the brink of nuclear war," Rodong Sinmun, the official newspaper of the North's ruling party, said in an editorial on Monday.

"How could we ever ignore the arrival of such dangerous forces to the South?" it said.

"The warmongers... should never forget that our forces stand fully ready to attack at once in line with operational plans approved by our top command," the newspaper added.

North Korean troops near the disputed Yellow Sea border have been ordered to strike back if "even a single shell drops" in their territorial waters, the North's army command said in a recent statement.

Any subsequent counterstrike would trigger an escalated military reaction that would see South Korea's border islands engulfed in a "sea of flames", it said.

The tense sea border off the west coast saw deadly naval clashes in 1999, 2002 and 2009. The North shelled one of the islands, Yeonpyeong, in November 2010, killing four South Koreans and sparking brief fears of a full-scale conflict.