"This is a dangerous provocative act of leading the acute situation on the Korean peninsula, which may spark off a physical conflict between the two sides by means of an accidental single shot," said Pyongyang's foreign ministry, as quoted by state media.

The joint US-South Korea "Freedom Shield 2025" exercise was set to kick off on Monday, and will involve "live, virtual, and field-based training", according to a US statement.

The exercise will run until March 21, the statement said.

Military cooperation between Seoul and Washington regularly invites condemnation from Pyongyang, where the government sees such moves as preparation for an invasion, and often carries out missile tests in response.

The latest exercise comes after two South Korean Air Force fighter jets accidentally dropped eight bombs on a village during a joint training exercise with US forces on March 6.

Fifteen people, including civilians and military personnel, were wounded in that incident, South Korea's National Fire Agency said.

Relations between Pyongyang and Seoul have been at one of their lowest points in years, with the North launching a flurry of ballistic missiles last year in violation of UN sanctions.

The two Koreas remain technically at war since their 1950-1953 conflict ended in an armistice, not a peace treaty.

The United States stations tens of thousands of soldiers in the South, in part to protect Seoul against Pyongyang.

The large-scale Freedom Shield exercises are one of the allies' biggest annual joint exercises.

In its statement on Monday, North Korea's foreign ministry dubbed the exercises "an aggressive and confrontational war rehearsal".

Last week, Pyongyang slammed the United States for "political and military provocations" over the visit of a US Navy aircraft carrier to the South Korean port of Busan.