The operation was a response to the recent North Korean provocations and sent a strong message of unity and determination against the continuous acts of aggression by Pyongyang, said a statement issued in Seoul by the US Naval Forces Korea (USNFK), EFE news reported.
USNFK Commander Rear Admiral Brad Cooper reaffirmed the US commitment to "remain by South Korea's side to defend against North Korea's unprovoked acts of aggression".
It was the first time US and South Korean vessels operated together in waters so close to the east coast of North Korea, CNN quoted a US Navy official as saying.
The ships were armed with long-range, precision, land-attack cruise missiles, the official said.
The one-day drill saw the US guided missile destroyer USS Spruance join ships, submarines, anti-submarine helicopters and patrol aircraft from the South Korean navy in waters east of the Korean Peninsula.
This new show of force by Seoul and Washington comes after the deployment of US bombers to South Korea twice, the last time on September 21.
"Our (Republic of Korea) ROK-US alliance will counter the North Korean nuclear development and SLBM threats with determination," Vice Adm. Lee Ki-sik, commander of the ROK Fleet, said in a statement.
The drill saw the presence of the Spruance and South Korean destroyers equipped with the Aegis missile defence system. Touted by manufacturer Lockheed-Martin as "the world's most advanced combat system", Aegis can track more than 100 targets at a time and is the only naval system capable of intercepting ballistic missiles.
After the bombers flew over South Korean territory following North Korea's fifth nuclear test on September 9, Pyongyang accused the US of escalating tensions in the region towards a nuclear war at a time of great conflict.
The latest test by Pyongyang was strongly condemned by the international community, and the UN Security Council is likely to impose new sanctions on North Korea.
Pyongyang, however, ignored the criticisms and defended its nuclear and missile development on grounds of self-defence against the US.
Since the Korean War (1950-53), the US maintains a military alliance with South Korea and is committed to defend it against any possible conflict with North Korea.
Meanwhile, experts disagree on whether the repeated show of force by the US can stop Pyongyang's nuclear testing.
South Korean officials believe that Pyongyang is already physically ready to carry out its sixth nuclear test.
The military displays show North Korea that "the US won't be intimidated by their pursuit of nuclear weapons, much less the threat to use them", David Straub, a former State Department Korean Affairs Director, told CNN.
Shows of force are also "useful in reassuring the South Korean government and people that the US has both the capability and the will to deter North Korea", Straub said.
But Victor Cha, Korea Chair at the Centre for Strategic and International Studies in Washington, said the movement of military assets into the region is part of a US strategy that is "as predictable as it is ineffective".
"With each missile and nuclear test, Kim Jong-un appears to be gaining confidence and certainty that the world will recognise North Korea as a nuclear state and deal with it on those terms," Cha said in Congressional testimony on September 14.
Andre Gerolymatos, coordinator of the Terrorism, Risk and Security Studies Program at Simon Fraser University, in British Columbia, Canada, told CNN that flyovers and exercises are "not sufficient to cause alarm" in North Korean leader Kim Jong-un.
"Like all bullies he only understands force," Gerolymatos said.
