"We are not concealing the fact that (North Korea's) revolutionary military, including strategic rocket forces, has placed not only South Korean enemy forces and US forces in the Korean peninsula but also Japan, Guam and even the US mainland within its target range," the North’s National Defense Commission said in a Tuesday statement.
It added that Pyongyang was ready to react to any attack with "nuclear for nuclear and missile for missile" strategy.
The statement came two days after Seoul said that it reached an agreement with Washington to extend the range of its missiles from the current limit of 300 km to 800 km.
The extension will not only bring the whole of North Korea but also parts of China and Japan within reach of Seoul's rockets.
Tensions have been high between the two Koreas since four South Koreans were killed on November 23, 2010, after North Korea fired dozens of artillery shells onto the populated small island of Yeonpyeong.
Seoul demanded an apology from North Korea over the deadly shelling of the island, while Pyongyang said it shelled the area as a result of provocations by Seoul.