The United States and South Korea have enough firepower to overcome North Korea if the current crisis were to escalate, according to analysts.

But the costs of war are so high that the US and its Asian allies are unlikely to choose the military option to defuse the situation.

Neither is a limited strike on the Yongbyon nuclear facility an attractive alternative.

North Korea's military

1 million man army 3,000 battle tanks 22 attack submarines 500 combat aircraft Scud-C and Nodong-1 missiles operational Taepodong 1 missile could strike Japan Source Jane's Information Group

N Korea's missiles

"There is no doubt that the US could conduct a fairly effective strike on the reactor, but there's too many problems that it could create," said Andrew Kennedy, head of the Asia Research Programme at the Royal United Services Institute (RUSI).

The biggest worries are that radioactive material from the Yongbyon reactor could drift into South Korea, while Pyongyang has warned that such a strike would lead to "full scale war".

Despite North Korea's moribund economy, a military showdown would be no pushover.

North Korea has an alarming array of conventional forces, with a one-million man army, thousands of artillery pieces trained on the South Korean capital Seoul, and a ballistic missile capability which is known to reach as far as Japan, and possibly even Alaska.

Despite North Korea's arsenal, however, Adam Ward from the International Institute of Strategic Studies (IISS) said it was clear that the US and South Korean forces would prevail in any conflict.

The allied troops were "numerically inferior but qualitatively far more superior," he said.

Gamble

Much of North Korea's arsenal dates back to the 1950-53 Korean War. For the impoverished hermit state it would be "very difficult to maintain these forces in a fighting manner", Mr Kennedy said, adding that there was "a big difference between 10,000 tanks and 10,000 tanks that work".

US strength

37,000 troops in South Korea 90 combat aircraft in S Korea, further 80-90 offshore Trident ballistic missile submarines S Korean armed forces of 560,000 men Source: Jane's Information Group

Even though Washington is thought to have the upper hand, North Korea is probably gambling that the price to the US and its allies would be too high.

Armed conflict would lead to a tremendous loss of life in South as well as in North Korea. Americans would be certain to be among the casualties, since 37,000 US troops are based in South Korea and many US businesses have offices and employees in Seoul.

In the face of these unpalatable facts, Washington appears intent on pushing for a diplomatic solution to the crisis.

Although the US has put some aircraft on alert to possibly reinforce its Pacific strength, Washington has also been sending diplomatic signals that it is willing to talk to North Korea.

The problem is that Pyongyang is far from predictable. Further threatening moves - such as test firing missiles or military mobilisations - cannot be ruled out.

"It is clear that North Korea has a long history of rhetorical flourishes" which do not necessarily amount to a threat, Mr Ward said, "but we cannot discount" a military response.