SEOUL, South Korea -- The United States and South Korea began their biggest combined military drills since 2018 on Monday, Seoul said -- a move likely to enrage North Korea, which has been ramping up its nuclear threats.
Washington is Seoul's key security ally and stations about 28,500 troops in South Korea to protect it from its nuclear-armed neighbour.
The two countries have long carried out joint exercises, which they insist are purely defensive but North Korea sees them as a rehearsal for invasion.
The Ulchi Freedom Shield exercise marks the resumption of large-scale training sessions after they were scaled back due to Covid-19 and a bout of failed diplomacy with Pyongyang.
"The significance of this joint exercise is rebuilding the South Korea-US alliance and solidifying the combined defence posture by normalising... combined exercises and field training," the defence ministry said.
Details of the drills that run from August 22 to September 1 have not been released, but they usually include field exercises involving aircraft, warships and tanks -- with tens of thousands of troops.
During a meeting last week, the allies agreed to "expanding the scope and scale of combined military exercises and training," noting the increased volume of North Korean missile tests.
This will start "with Ulchi Freedom Shield... to bolster combined readiness," they said in a joint statement.
Analysts say North Korea may use the drills as a reason to conduct more weapons tests.
Earlier this month, Pyongyang warned it would "wipe out" Seoul authorities, who it blamed for a recent Covid-19 outbreak in the isolated country.
That threat came less than a month after Kim Jong Un said his country was "ready to mobilise" its nuclear capability in any war with the United States and South Korea.
North Korea has conducted a blitz of sanctions-busting tests this year, including firing an intercontinental ballistic missile at full range for the first time since 2017.
Washington and Seoul officials have also warned that the isolated regime is preparing to carry out what would be its seventh nuclear test.