North Korea's military, founded 81 years ago Thursday, is older than the country itself. It began as an anti-Japanese militia and is now the heart of the nation's "military first" policy.

Late leader Kim Jong Il elevated the military's role during his 17-year rule; South Korea estimates he boosted troop levels to 1.2 million soldiers. The military's new supreme commander, Kim Jong Un, gave the Korean People's Army a sharpened focus this year by instructing troops to build a "nuclear arms force." Yet the army is believed to be running on outdated equipment and short supplies.

The secretive army divulges few details about its operations, but here is an assessment from foreign experts of its strengths and weaknesses:

ARTILLERY

North Korea provided a chilling reminder of what its artillery is capable of when it showered a front-line South Korean island with shells, killing four people in November 2010 and underscoring the threat that its artillery troops pose at the disputed sea border.

South Korea says North Korea has more than 13,000 artillery guns, and its long-range batteries are capable of hitting the capital Seoul, a city of more than 10 million people just 30 miles (50 kilometers) from the border.

"North Korea's greatest advantage is that its artillery could initially deliver a heavy bombardment on the South Korean capital," Mark Fitzpatrick, a former U.S. State Department official now with the International Institute for Strategic Studies, said in an email.

South Korea's defense minister estimates that 70 percent of North Korean artillery batteries along the border could be "neutralized" in five days if war broke out. But Sohn Yong-woo, a professor at the Graduate School of National Defense Strategy of Hannam University in South Korea, said that would be too late to prevent millions of civilian casualties and avert a disastrous blow to Asia's fourth-largest economy.

SPECIAL FORCES

Experts believe guerrilla warfare would be the North's most viable strategy in the event of conflict, since its conventional army suffers from aging equipment and a shortage of firepower.

Seoul estimates North Korea has about 200,000 special forces, and Pyongyang has used them before.

In 1968, 31 North Korean commandos stormed Seoul's presidential Blue House in a failed assassination attempt against then-President Park Chung-hee. That same year, more than 120 North Korean commandos sneaked into eastern South Korea and killed some 20 South Korean civilians, soldiers and police officers.

In 1996, 26 North Korean agents infiltrated South Korea's northeastern mountains after their submarine broke down, sparking a manhunt that left all but two of them dead, along with 13 South Korean soldiers and civilians.

"The special forces' goal is to discourage both the United States and South Korea from fighting with North Korea at the earliest stage of war by putting major infrastructure, such as nuclear plants, and their citizens at risk," said Kim Yeon-su, a professor at Korea National Defense University in Seoul. "The North's special forces are a key component of its asymmetric capabilities along with nuclear bombs, missiles and artillery. Their job is to create as many battlefronts as possible to put their enemies in disarray."

ON LAND, BY SEA AND IN THE AIR

In March 2010, 46 South Korean sailors died in a Yellow Sea attack on their warship that Seoul blamed on a North Korean submarine. Pyongyang denies involvement. Separately, since 1999, North and South Korean navies have fought three bloody skirmishes near their disputed western maritime border. Experts say those battles show while the South has an edge in naval firepower and technology, the North relies on the element of surprise.

North Korea has 70 submarines while South Korea has 10, according to Seoul's Defense Ministry. The most menacing threats from the North's navy are small submarines that would deposit commando raiders along the South Korean coast, said John Pike, head of the Globalsecurity.org think tank.

North Korea also has 820 warplanes, more than South Korea, though Seoul is backed up by American air power. The South says most of the North's aircraft are obsolete. North Korea also suffers chronic fuel shortages that have forced its air force to cut sorties, experts say.

"North Korea would not be able to prosecute a full-fledged war for very long," Fitzpatrick said. "Its biggest problem is that North Korea would quickly lose control of the skies because of the vastly superior (South Korean) and U.S. air forces. The reported number of North Korean aircraft is meaningless, because many of them cannot fly, and North Korean pilots have little training in the air."

The U.S. stations 28,500 U.S. troops in South Korea and has recently flown nuclear-capable stealth B-2 bombers and F-22 fighter jets during joint drills in a show of force aimed at deterring North Korea.

Logistics and supplies are another issue. Heavy equipment deployed by naval and air forces requires extensive repairs, especially on rugged terrain like the Korean Peninsula. South Korea's Defense Ministry estimates North Korea's wartime resources, mostly stored underground, would last only two to three months.

"North Korea's only chance of winning any war depends on how quickly it can end one," Sohn said.

North Korea could try to compensate for its lack of effective equipment with sheer manpower. North Korea, a country of about 25 million, has an estimated 7.7 million reserves.

MISSILES AND NUCLEAR WEAPONS

North Korea says it needs to develop nuclear weapons as a deterrent against U.S. aggression. It has conducted three underground nuclear tests since 2006, the most recent in February.

Pyongyang is believed to have enough weaponized plutonium for four to eight nuclear bombs, according to Siegfried Hecker, a nuclear expert with Stanford University's Center for International Security and Cooperation.

But he doubts Pyongyang has mastered the technology to tip a missile with a nuclear warhead. "I don't believe North Korea has the capacity to attack the United States with nuclear weapons mounted on missiles and won't for many years," he said on the website of Stanford University's Freeman Spogli Institute for International Studies this month.

Bruce Bennett, a Rand Corp. expert, said earlier this month that it's very unlikely the North has a nuclear missile capable of hitting the U.S. but said there is a "reasonable chance" that Pyongyang has short-range nuclear missile capability.

CHEMICAL AND BIOLOGICAL WEAPONS

North Korea denies it runs any chemical and biological weapons programs. South Korea claims that Pyongyang has up to 5,000 tons of chemical weapons.

The IISS says that although the figures are "highly speculative," the North probably does possess chemical and biological arms programs.

"Whatever the actual status of North Korea's chemical and biological capabilities, the perception that it has, or likely has, chemical and biological weapons contributes to Pyongyang's interest in creating uncertainties in Washington, Seoul and Tokyo and raises the stakes to deter or intimidate potential enemies," it said on its website. North Korea is not a signatory to the Chemical Weapons Convention, but it has acceded to the non-binding Biological and Toxin Weapons Convention.