South Korea has made it clear it is marching ahead with its joint military exercises with the US despite the ongoing sports diplomacy through which the rogue North Korean regime has agreed to send its athletes to the upcoming Winter Olympics.

In a sharp rebuke to Pyongyang's earlier calls to scale down Seoul's joint military activities with Washington in the region, the South has hinted the size and strength of the exercises will not be reduced.

"The exact date and size of the planned joint exercises cannot be disclosed, but they will be carried out after the close of the Olympics," Choi Hyun-soo, a spokeswoman for the defence ministry, told reporters.

The US and South Korea, key allies facing an increasing threat from North Korea, usually conduct Key Resolve and Foal Eagle at the start of Spring season in the country. But, the two countries have earlier said they are delaying the exercises due to the PyeongChang Winter Olympics and Paralympics in February.

Thousands of troops from both sides and strategic assets such as fighters and sophisticated warships are usually mobilised for the annual exercises.

Joint military drills are a serious bone of contention between North Korea and its adversaries as the reclusive Kim Jong-un regime considers such acts as a rehearsal for a full-scale invasion against North Korea. But, the US and South Korea have repeatedly denied those accusations and insisted that these exercises are meant to enhance the combat readiness of their troops.

While the North Korean regime has previously called on South Korea to permanently abandon these exercises with the US, Russia and China - key geopolitical backers of Pyongyang - have urged Washington and Seoul to temporarily suspend the events in return for improving ties with the defiant regime.

Seoul's decision to go ahead with military exercises with Washington comes days after the Donald Trump administration in the White House announced a fresh round of sanctions against North Korea.

US South Korea joint drill
US Navy crew members walk on the deck of the USS Ronald Reagan, a Nimitz-class nuclear-powered super carrier, during a joint naval drill between South Korea and the US - File photo Kim Hong-Ji/Reuters file photo