The latest Hyunmoo-2C missile, with a range of 800km, was shown publicly for the first time.
Tensions on the Korean peninsula have escalated in recent weeks as North Korea’s leader Kim Jong-un and US President Donald Trump exchanged threats and insults over the North’s nuclear and missile development programme.
South Korea’s national security adviser Chung Eui-yong said on Thursday he expects the North to engage in more provocative acts early next month with the anniversary of the founding of the communist party.
The US and South Korea are technically still at war with North Korea because the 1950-53 Korean conflict ended with a truce, not a peace treaty.
The South’s Armed Forces Day usually falls on October 1 and commemorates the day in 1950 when its forces broke through the 38th parallel border during the war against invading North Korea.
However this year’s ceremony was held earlier because of national holidays taking place next week.