The Navy's elite UDT/SEALs rescued the crew of a South Korean freighter from Somali pirates on Friday, but their success masks cracks in the structure of South Korea's dwindling special forces.

The Army, Navy, Air Force, and Marine all have special forces, but their combined number is less than 20,000. The top unit is the Army Special Warfare Command. About 10,000 SWC troops are tasked with infiltrating deep behind enemy lines for reconnaissance and surveillance, destruction of key military facilities, sabotage and kidnapping of enemy VIPs.

Within the Army SWC, the 707th Special Mission Battalion is the elite commando. It combats terrorism, protects VIPs and carries out top-secret operations.

The SWC also plays a role in UN peacekeeping operations, including the Dongmyeong Unit stationed in Lebanon. The Amy also has a special operations brigade whose duties are to mop up North Korea's light infantry troops if they infiltrate South Korea.

The Navy's UDT/SEAL unit is modeled after the U.S.' UDT. The unit is famous for its intensive training. For 138 hours during one training week, UDT/SEAL members have to practice rowing a rubber boat, adjusting to the mudflat environment, and running at a canter incessantly without getting a wink of sleep. They have to eat on the hoof while carrying an 85 kg rubber boat on their heads.

The Air Force's combat controllers are another elite troop. During wartime, they too infiltrate behind enemy lines ahead of airborne troops or airlift operations to guide planes so that they can drop troops and equipment without a hitch.

They undergo special training with the 707th Special Mission Battalion and the Navy UDT/SEAL and mountain rappelling training at the Marine Corps for three years, in addition to a yearlong training course of their own.

The search battalion is rated as the top unit in the Marine Corps. Marine recruits can join the search battalion only if they finish two weeks of basic training, seven weeks of special training, and three weeks of basic parachute training at the search battalion's training camp after the basic six-week training at Marine boot camp.

But while South Korea's special forces are recognized for their world-class capabilities, experts point out that there is still a great deal of room for improvement. For one thing, they depend on the U.S. military for equipment, because they are in short supply of special-purpose transport aircraft or helicopters needed for infiltration.

For another, long-serving special forces members have few chances of promotion, meaning some talented soldiers are reluctant to serve in the special forces.

"The hostage rescue operation is an opportunity for the military and the government to shed new light on the strategic value of the special forces," a military source said. "The government should work out a policy to improve their combat capabilities."