North Korea said Tuesday it possessed "strategic rocket forces" capable of striking the US mainland, as it responded to a new US-South Korean deal to extend the range of the South's missile systems.
In a series of bulletins released on the official Korean Central News Agency (KCNA), the spokesman of the National Defense Commission also said Pyongyang was ready to match any enemy, "nuclear for nuclear, missile for missile".
The warnings came two days after South Korea announced an agreement with the United States to almost triple the range of its missiles to cover the whole of North Korea.
"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 spokesman said.
North Korea is known to have an inter-continental ballistic missile (ICBM) in development -- the Taepodong-2 -- but it has never been tested successfully.
In April, the North carried out a failed rocket launch in what it said was a bid to put a satellite into orbit.
The US and United Nations condemned the launch as a disguised ballistic missile test, saying the rocket was simply a three-stage variant of the Taepodong-2.
After the failed test, North Korea raised eyebrows by displaying what appeared to be a new set of ICBM missiles at a military parade to mark the 100th birthday of the North's late founder Kim Il-Sung.
But Western military analysts and UN sanctions experts concluded that the display models were simply mock-ups.
South Korean analysts suggested Tuesday's comments were most likely military bluster prompted by Sunday's announcement of the new US-South Korea missile deal.
"It could be a bluff, as there is no evidence that North Korea has succeeded in tests of a missile with a range long enough to hit the US mainland," said Yun Duk-Min, a professor at Korea National Diplomatic Academy.
"It might also be aimed at boosting military morale and rallying support behind (new leader) Kim Jong-Un.
"North Korea's military is suffering from a breakdown in discipline and public resentment is rising amid worsening food shortages following natural disasters this summer," Yun said.
The new agreement with the United States allows the South to deploy missiles with a range of 800 kilometres (500 miles), up from the current limit of 300
The extension not only brings the whole of North Korea within reach of Seoul's rockets, but also parts of China and Japan.
The US stations 28,500 troops in South Korea and guarantees a nuclear "umbrella" in case of any atomic attack. In return, Seoul accepts limits on its missile capabilities.
An agreement signed with the United States in 2001 had restricted Seoul to rockets with a range of 300 kilometres and a payload of 500 kilograms (1,100 pounds).
Given the ambitions of nuclear-armed North Korea's own missile programme, the South had long argued for the limits to be extended, and negotiations took on a new
urgency after the North's failed rocket launch in April.
"The North must have been greatly shocked at the announcement on Sunday," said Baek Seung-Joo, at the Korea Institute for Defence Analyses.
"To extend South Korea's missile ranges means the South would be able to mount pre-emptive, surgical strikes on any of the nine North Korean missile bases if necessary."