For nearly twenty years the most powerful tank of the South Korean military was the Russian-made T-80

North Korea famously maintains a giant army that also fields some 4,000 to 6,000 tanks. The mainstay of its tank fleet are older Soviet-made tanks along with domestic and Chinese copies of the same.

Yet ironically its archenemy South Korea likewise fields Soviet or Russian-made tanks which furthermore are far more modern and far superior to the 1960s era Soviet tanks that the North has. How did this come to be?

In the 1980s South Korea was continuosly reaching out to China and the Soviet Union hoping to establish working relations with them and possibly drive a wedge between them and North Korea.

The Soviets wanted none of that at first, but by the late 1980s which were marked by radical change under Gorbachev they were ready. Since the last years of Gorbachev were also marked by a severe economic crisis Moscow also ended up $1.5 billion in debt to Seoul.

When the Soviet Union was dissolved by Yeltsin in 1991 Russia as the sole legal successor inherited its UN Security Council seat, its atomic weapons, and its foreign debt.

Nonetheless, Yeltsin's Russia, which if anything was even more cash-strapped than the Soviet Union had been, was in no hurry to repay these loans, at least not with cash.

Moscow offered Seoul, as well as its other creditors, to repay debt with the one thing it had in abundance: state-of-the-art weaponry. Seoul at first resisted but by 1994 it agreed that one half of the debt would be settled by a transfer of Russian arms.

South Korea, despite its intimate military ties to the US, actually accepted the Russian offer sooner than many of the other Russian creditors. The reason was that once it got over the guile of the Russians Seoul realized this was actually a pretty good opportunity for them.

At the time South Korea already possessed a vibrant manufacturing sector, but had tried its hand at assembling serious military hardware only recently and with mixed success.

It was looking to develop its domestic arms manufacturing, but the US which has a vast military-industrial complex of its own was not super enthusiastic about providing a helping hand.

Russians, however, were offering their very latest technology – yes provided that South Korea makes its purchases in meaningful quantity but without tying transfers to mega-million deals.

Thus the Korean military drew a list of what it wanted the most: 33 T-80U tanks, 33 BMP-3 infantry fighting vehicles, over a thousand anti-tank "Metis" missile launchers and dozens of anti-aircraft "Igla" missile launchers. All were dutifully delivered in 1995-96.

Now one may ask how come? How come Russia was willing to arm South Korea with tanks that far outclassed anything its traditional all North Korea had? And how come it was so cavalier about transferring its latest in tank technology to a close US ally?

The answer to the first question is that in the 1990s Moscow had essentially abandoned North Korea as it instead courted the cash-rich South, in much the same way Seoul (for different reasons) courted the Soviet Union in the 1980s.

The answer to the second question lies in the fact that in 1992 Britain obtained five T-80s and sent one of them on to Americans. Thus the tech Russia was now transferring to Seoul would be new to South Koreans, but it was not anything the Americans had not already studied in detail.

The Russian tanks the South Korean military received boasted a 125mm gun that was considerably more powerful than the 105mm and 115mm guns of their M-48 and K1 tanks. The Russian tanks were also more mobile thanks to their powerful (if not terribly economical) gas-turbine engines.

On the other hand, the South Koreans noted the Russian optics were inferior and eventually replaced them with western-designs. Also Koreans, used to their tall American-designed tanks (K1 was produced in Korea but was drawn up by Chrysler) found the compact, just 2.2 metres tall, T-80s rather hard on the crew.

Nonetheless the South Korean military was fond enough of the T-80 that during the second round of the arms-for-debt program in 2002 it asked for 10 more units which were delivered in 2005.

T-80 remained South Korea's hands down most potent tank for nearly 20 years, until 2014 when its domestically-produced K2 which boasts a 120mm gun and is its equal begun entering service. The T-80 is set to remain in service for a very long time too seeing how South Korea still fields hundreds of utterly obsolete M-48 tanks.

If the T-80 represented a very noticeable boost in South Korean military capabilities this was even more true of the BMP-3. It was South Korea's first infantry fighting vehicle and as such completely outclassed its armored personel carriers, the American-made M113 and the South Korean K200, both of which were slow and undergunned.

South Korea organized its first mechanized infantry batallion around its first 33 BMP-3s. In 2002 it asked for additional 37 machines which were delivered in 2005.

By now Russian optics had improved (including due to cooperation with the French). South Koreans were sufficiently impressed with the sighting system of the 2005 batch that they promptly purchased the same optics for their 1995-96 batch.

Actually it was getting their hands on BMP-3s which made the South Koreans realize just how far behind they were in this type of equipment. In 1999 Seoul begun developing its own infantry fighting vehicle, the K21 which begun entering service in 2009.

Compared to a BMP-3 the K21 is nearly 50% heavier and therefore better armored. However, the South Koreans have not been able to recreate the wateborne abilities of the BMP-3. Unlike the latter, the K21 (like the America M2 Bradley) is not fully amphibious but requires some 30 minutes of preparation to cross serious obstacles.

The BMP-3 therefore is also set to remain in service in South Korea for decades longer seeing how it is not only vastly superior to the 1,700 K200 vehicles in service, but also brings something to the table which the newer and more expensive K21 does not.