The military muscle-flexing is directed at Pyongyang in the wake of continued missile and nuclear testing, the news agency Yonhap reported.
Taking part in the six-day exercises will be the nuclear-powered US aircraft carrier Ronald Reagan, as well as the destroyers Curtis Wilbur (DDG-54), John S. McCain (DDG-56), Fitzgerald (DDG-62), Stethem (DDG-63) and Barry (DDG-52).
Additionally, "the allies' navies plan to mobilize dozens of warships and submarines for the drills", such as Ticonderoga-class Aegis missile cruisers, P-3 and P-8 maritime patrol aircraft, Apache helicopters and FA-18C Hornet fighter jets, according to Yonhap.
"The 'Invincible Spirit' exercise is aimed at showing the allied forces' strong commitment to counter relentless provocations by the North and improve their maritime interoperability," Yonhap quoted a Navy spokesman as saying.
According to the spokesman, "in waters off the southwestern coast of the Korean Peninsula, the aircraft carrier strike group will conduct anti-submarine, anti-aircraft and precision-guided striking operations."
In this vein, Yonhap mentioned a spate of missile tests that had been conducted by Pyongyang earlier this year in defiance of UN sanctions imposed on North Korea after its fourth nuclear test in January. It was followed by Pyongyang's fifth such test on September 9, which proceeded despite the warnings of the international community, according to Yonhap.
Seoul and Washington staged a massive joint naval exercise also codenamed Invincible Spirit in July 2010, in the wake of the sinking of the South Korean corvette Cheonan, which Seoul claims was the work of North Korea. Pyongyang vehemently denies all the accusations, which it says hold no water.
Earlier this year, Washington and Seoul held what media outlets described as the largest-ever joint exercises of the two countries amid increased tensions on the Korean Peninsula.
As many as 15,000 US troops and about 290,000 South Korean soldiers took part in Key Resolve and Foal Eagle, two joint US-South Korean military exercises that were held between March and April.
The exercise presupposed dispatching the US overseas forces to the Korean Peninsula and practicing the elimination of Pyongyang's weapons of mass destruction.
Pyongyang responded by saying that it is ready to launch a "preemptive nuclear strike" at the United States and South Korea at the slightest sign of provocation.
The North Korean military warned Seoul at the time that "the situation on the Korean Peninsula is so tense that a nuclear war may break out any moment," and vowed to "hold their bayonets more tightly."