The Democratic People's Republic of Korea(DPRK) said Tuesday that the U.S. mainland is within the target range of its strategic rocket forces, the official KCNA news agency reported.

A spokesman for the National Defense Commission of the DPRK announced that the country is equipped with strategic rocket forces now able to place the U.S. mainland territory, South Korea, Japan and Guam within its target range.

"We are well prepared to fight with nuclear (weapons) against any nuclear (attacks) by the U.S. and its followers," said the spokesman, vowing to launch all-out efforts to match the United States and South Korea.

"Nuclear for nuclear, missile for missile," he said.

The spokesman lashed out at the U.S. ambition "to lay strategic siege network to Asia," adding that Pyongyang "will show the real bitterness of a war that the world has never known or imagined."

The announcement came after the South Korean presidential office said Sunday that under a revised pact with the United States, Seoul planned to develop ballistic missiles with a tripled range of 800 kilometers, which could cover the entire peninsula, as part of its efforts to better respond to perceived missile threats from the DPRK.

Critics said South Korea's extension plan ran counter to its commitment as a member of the global arms control agreement, known as the Missile Technology Control Regime (MTCR), an informal association that aims at curtailing the spread of unmanned delivery systems that could deliver weapons of mass destruction.

However, the White House on Sunday defended South Korea's pursuit of longer-range missiles.