South Korea has warned that it would retaliate against any hostile action from North Korea.
Army General Kim Yong-hyun said there would be "resolute retaliations" should South Korean lives be under threat.
"If North Korea carries out provocations that threaten the lives and safety of South Koreans, our military will carry out strong and resolute retaliations," he told reporters.
North Korea said on Tuesday that they would end the truce in place since 1953 on March 11.
The US has tabled a resolution at the UN Security Council calling for new sanctions against Pyongyang.