A private U.S. intelligence firm has released a report looking into a military strike scenario against North Korea's nuclear facilities, inviting angry reaction from the communist nation.

In a five-part report titled, "Removing the Nuclear Threat," the information firm Stratfor detailed possible military means for a strike and possible responses from the North.

Pyongyang has bristled at the report, saying Wednesday that it shows a surprise preemptive attack and armed invasion are in "the full-dress process of examination and preparation." The North also warned it will further bolster its nuclear capabilities.

The Stratfor report said B-2 bombers and F-22 fighters would "form the backbone of any anti-nuclear operations."

"The North Koreans have a dense and interlocked air defense network, but the force is obsolete and largely incapable of adequately defending against or even detecting full-spectrum stealth aircraft such as the U.S. B-2 bomber and F-22 tactical fighter," the report said.

"Given enough time, the United States could assemble upward of 10 B-2 bombers for a deep-strike mission into North Korea. The shorter combat radius of the F-22 would limit the number of aircraft available for the task, necessitating the deployment of the fighter to regional airfields," it said.

The U.S. could deploy 24 F-22 aircraft for the mission using airfields in Japan and South Korea, the report said. Each F-22 can be equipped with two 450-kilogram GBU-32 JDAM bombs, while each B-2 would deploy with either 16 900-kilogram GBU-31 JDAMs or a pair of massive 13,600-kilogram GBU-57 Massive Ordnance Penetrators to reach deep underground bunkers, it said.

In addition, the U.S. can park two of its four Ohio-class cruise missile submarines off the North Korean coast and fire BGM-109 Tomahawk land attack cruise missiles to strike remaining targets, the report said.

The report said that the North is expected to strike back.

"Pyongyang will do everything it can to impose a cost on any belligerent force. If the United States wishes to denuclearize North Korea, it will have to accept the consequences, as will South Korea and possibly even Japan," it said.

The North's most powerful tool is artillery, it said, adding that it cannot level Seoul as some reports have claimed, but it could do significant damage.

"After a strike, North Korea's most immediate and expected method of retaliation would center around conventional artillery," it said. "Many of the North's indirect fire systems are already located on or near the border with South Korea. By virtue of proximity and simplicity, these systems have a lower preparatory and response times than air assets, larger ballistic missiles or naval assets."

The report said, however, that an initial mass volley imposes great risk to the artillery systems themselves, making them vulnerable to counter-battery fire, which means that casualty rates would drop significantly after the initial barrage, "limiting potential civilian casualties to thousands of dead rather than tens of thousands." (Yonhap)