North Korea has said that recent missile launches were in protest against the joint exercises, which it says are provocative and a rehearsal for an invasion.
South Korea and the US say the exercises are defensive and needed to counter the North’s threats.
The US and its allies believe North Korea could be about to resume nuclear bomb testing for the first time since 2017. South Korean President Yoon Suk-yeol has said the North has completed all necessary technical preparations for an underground detonation at its Punggye-ri Nuclear Test Site, which has been officially shuttered since 2018.
North Korea conducted six nuclear tests at the site from 2006 to 2017.
The head of the United Nations nuclear watchdog on Thursday said a seventh North Korea nuclear test would be further “confirmation of a programme which is moving full steam ahead in a way that is incredibly concerning”.
South Korea has warned that a resumption of nuclear testing by North Korea would have to be met with an “unparalleled” response from the allies, but neither it nor the US has given details.