South Korea's troop level would hover around 150,000-200,000 if the country abandons its conscription system for a volunteer force, a state-run think tank said Sunday.

The findings by the Korea Institute for Defense Analyses based on an assessment of other countries that maintain a volunteer military showed on average that 0.4 percent of the population serves in the armed forces, which is roughly half of the number for places that rely on mandatory conscription.

"In the United States, it stands at 0.42 percent of the population, while in Europe, it is lower at 0.26 percent," the KIDA report said.

It said if the average number holds true for South Korea, which has a population of around 50 million, the size of the country's standing military would not exceed 200,000.

"Even this number may be difficult to reach and maintain," it predicted.

At present South Korea's military accounts for about 1.3 percent of the populace, which is significantly smaller than the

4.8 percent for North Korea, which has less than half of the population, and 2.2 percent for Israel.

The research institute also said country's that have a volunteer military spend more on defense than those that run a conscript force.

The so-called defense budget injection rate or the per capita GDP allocated to each troop for a volunteer force was 1.6 times larger than that spent on a conscript military.

"Countries like the United States that have a volunteer military have per capita GDP exceeding $30,000 and spend considerable sums of its budget on defense," KIDA said. "If this formula is applied here, South Korea would have to spend much more on defense or cut troop levels."

It, however, said that cutting troops is not an easy option in light of greater threats from the North. Seoul said it will maintain a 522,000-strong military force in 2022 to meet its security needs.

The latest report then pointed out that the country faces challenges because its population is decreasing, which will reduce the overall recruiting pool.

KIDA said that if the term of service is reduced to 18 months from around 21 months for the Army at present, the total size of the military would have to be adjusted down to under 500,000 in 2022.

"Taking into account the difficult security situation surrounding the country, there is a need to freeze the service period and maintain the current conscription system to hold onto an adequate military force," the research institute said. (Yonhap)