The United States and South Korea began an annual joint military exercise Monday, despite angry threats from North Korea.
As many as 80,000 U.S. and South Korean forces are taking part in the computer-generated Ulchi Freedom exercise, which simulates a response to a military invasion by the North.
The exercise is taking place amid heightened tensions on the peninsula after two South Korean soldiers were maimed when landmines exploded as they were patrolling the demilitarized zone separating the two rivals.
Seoul blamed Pyongyang for planting the mines, and resumed propaganda broadcasts via loudspeakers near the countries' tense border for the first time in over a decade on Saturday.
South Korean broadcasts were aimed at emphasizing that the mine blast was provocation committed by North Korea and relaying messages about the superiority of Seoul-style democracy as well as world news and weather forecasts, the South Korean Defense Ministry official said.
The North has rejected South Korea's accusations. It said the broadcasts and the exercise both amount to a declaration of war, and has promised to take the "strongest military counteraction" in response.
On Monday, North Korea began its own loudspeaker broadcasts on the eastern part of the border, according to a South Korean Defense Ministry official who spoke on condition of anonymity because of department rules.
The official gave no further details. But South Korean public broadcaster KBS, citing an unidentified military official, reported that the North Korean broadcasts mainly included slanders against South Korea and praises for North Korea's political system.
South Korean President Park Geun-hye on Monday called for a strong military readiness on the Korean Peninsula.
"However, North Korea distorts and condemns the essence of the Ulchi exercise every year, continuing military threats," Park said.
'Need to be prepared'
"As far as the North's hostile attitude and provocative threats continue, we need to be prepared with a strong deterrent to counter the North, and the Ulchi exercise is a great opportunity to check and examine our preparatory position for securing our citizens' safety and the national security,” she said.
Seoul and Washington have described the joint military exercises as purely defensive in nature.
The Koreas' mine-strewn DMZ is the world's most heavily armed border, with hundreds of thousands of combat troops facing each other. It's a legacy of the 1950-53 Korean War, which ended with an armistice, not a peace treaty.
Some material for this report came from AP.