The South China Morning Post quoted military officials describing this as a clear warning to North Korea, which involve three U.S. aircraft carriers.
The drills began in waters off South Korea's eastern coast.
This came amid the U.S. President Donald Trump's Asia visit, which was largely focused on about the North Korean nuclear threat.
Earlier, Chinese President Xi Jinping and President Trump reiterated firm commitment to achieving denuclearisation of the Korean Peninsula and working towards a solution through dialogue and negotiation.
Currently, he is in Vietnam where he took part in Asia-Pacific Economic Cooperation (APEC) Summit.
The APEC summit, taking place this year, is focused on regional trade, with particularly attention on the TPP, the reports said.
APEC brings together 21 economies from the Pacific region. (ANI)