North Korea said Saturday its military is ready to pre-emptively attack and "liberate'' the South if it sees signs that American and South Korean troops involved in annual joint military drills are attempting to invade the North.

The declaration from General Staff of the North's Korean People's Army on state media is the latest outburst over the drills that the U.S. and South Korea say are defensive and routine. At the start of the drills on Monday, the North warned of an indiscriminate "pre-emptive nuclear strike of justice'' on Washington and Seoul.

The KPA said it will counter the drills by the United States and South Korea it says are aimed at advancing into Pyongyang with plans to ``liberate the whole of South Korea including Seoul'' and also that it is capable of executing "ultra-precision blitzkrieg'' strikes against enemy targets. 

In response to North's statement, South Korea's Joint Chiefs of Staff called for North Korea to stop its threats and ``rash behavior'' and warned that a provocation from the North would result in the destruction of its highest leadership. 

A pre-emptive large-scale strike by North Korea against the South is highly unlikely when that would almost certainly bring to an end the authoritarian rule of leader Kim Jong Un given the likely military response of the U.S. and South Korea.

Analysts say the North's bellicose rhetoric is also intended for its domestic audience to display government strength ahead of a major meeting of the ruling party in May. It is expected that Kim will use the Workers' Party convention, the party's first since 1980, to announce important state goals and shake up the country's political elite to further consolidate his power.

North Korea has condemned the annual military drills staged by Seoul and Washington in South Korea, calling them preparations for an invasion. This year, the drills follow the North's recent nuclear test and long-range rocket launch. (AP)