The announcement came despite Pyongyang's threat to retaliate again, while Russia and China expressed concerns over rising tensions on the divided peninsula.
The North warned on Friday it would strike even harder than before if the South went ahead with the exercises, which are expected to take place tomorrow. Four people died last month in the North's attack on Yeonpyeong island near the tense ocean frontier.
The US supports South Korea, saying the country has a right to conduct such a military exercise. However, Russia's foreign ministry expressed its "extreme concern" over the drills and urged South Korea to cancel them to prevent a further escalation of tensions.
The Russians also urged North Korea to demonstrate maximum restraint and refrain from acting in a way that could lead to a repeat of last month's artillery exchange with the South.
China, the North's key ally, said it was firmly against any acts that could worsen already-high tensions on the Korean peninsula.
"In regard to what could lead to worsening the situation or any escalation of acts of sabotage of regional peace and stability, China is firmly and unambiguously opposed," Chinese foreign ministry spokeswoman Jiang Yu said.
China's vice foreign minister, Zhang Zhijun, also warned that the situation on the Korean peninsula is "extremely precarious."
South Korea's joint chiefs of staff said that marines would go ahead with the drills as scheduled and that the military was ready to respond to any possible provocation.
Foreign ministry spokesman Kim Young-sun said that the drills are defensive in nature and are not aimed at stoking regional tensions.