South Korea spent $21.9 billion (about 20,367 billion won) on military build-up in 2006, ranking at the 11th in the world, according to a military affairs research institute in the capital of Sweden.
The figure accounts for 2 percent of world defense spending totaling $1,204 billion, the Stockholm International Peace Research Institute (SIPRI) reported in its Yearbook 2007 on armaments, disarmaments and international security released Monday.
The world's total military spending for 2006 was 3.5 percent up from the previous year's $1,118 billion, or 37 percent up from 1997's figure.
SIPRI has included North Korea, which conducted underground nuclear tests last October, in the list of nuclear powers for the first time.
The United States topped the list with $528.7 billion, or 46 percent of the world, followed by Britain at $59.2 billion. France, China and Japan rounded out the top five nations at $53.1 billion, $49.5 billion and $43.7 billion, respectively. China outnumbered Japan for the fist time in the ranking of military spending.
Other countries spending more in the military build-up than Korea were Germany ($37 billion), Russia ($34.7 billion), Italy ($29.9 billion), Saudi Arabia ($29 billion) and India ($23.9 billion).
Trailing South Korea were Australia ($13.8 billion), Canada ($13.5 billion), Brazil ($13.4 billion) and Spain ($12.3 billion).
The institute also calculated the spending according to purchasing power parity (PPP), based on comparison to the U.S.
China came in second in this calculation with $188.2 billion, followed by India ($114.3 billion). Russia and Britain were the other two in the top five.
South Korea ranked 11th under PPP as well, with the spending estimated at $30.1 billion.
In naming world's nuclear forces, the institute cited five states _ China, France, Russia, Britain and the U.S. _ under the non-proliferation treaty (NPT) as owning more than 26,000 nuclear warheads.
India, Pakistan and Israel are "de facto" nuclear weapon states outside the NPT.
North Korea made clear its intent to obtain nuclear capability, the institute said, but its detonation in October last year is widely believed to have been only a partial success.
"It raised doubts about whether North Korea could manufacture operational nuclear weapons," the institute said.