The deployment of T-80 U tanks and BMP-3 combat vehicles will bolster South Korea's capability to deter any aggression by North Korea, which relies on Russian-built weapons for its ground forces, the defense ministry said.
"This will be the first deployment of Russian weapons in front-line areas," a ministry official told AFP.
North Korea deploys more than 6,000 tanks and armored vehicles along the heavily armed border with South Korea. The two Koreas are still technically at war.
T-62 tanks and BMP series vehicles are the mainstream of North Korean ground forces, while South Korea is heavily dependent on US-designed equipment.
South Korea began purchasing Russian weapons in 1996 in repayment in kind to offset part of a loan to the former Soviet Union.
As of June last year, Russia has paid back 460 million in its debt service to South Korea in the form of military equipment and raw materials including uranium.
South Korea agreed last year to write off 660 million dollars of the amount due and will allow the remaining 1.58 billion dollars in principal and overdue interest to be repaid over the next 23 years.
Russia, a Cold War ally of communist North Korea, has shipped some 60 tanks and armored vechies to South Korea and plans to sell more.
President Roh Moo-Hyun, who took office a year ago, has promised to reduce South Korea's reliance on a US security umbrella.
Some 37,000 US troops are stationed in South Korea under a mutual defense pact dating back to the 1950-53 Korean War.
But the allies are locked in talks on the relocation of American troops, including a 15,000-member US infantry division in the frontline which is seen here as deterring North Korea's 1.1 million strong army.