South Korea's military has warned North Korea to immediately stop preparations for the launch of a military reconnaissance satellite.
The South Korean and US militaries are on high alert as Defense Minister Shin Won-sik said on Sunday that the launch could take place within a week or before November 30.
South Korea's Joint Chiefs of Staff said in a statement issued on Monday that if Pyongyang pushes ahead with the plan, the military would take necessary measures to protect the lives and safety of South Korean people.
The statement did not mention details of the measures. But it said the 2018 inter-Korean military agreement aimed at easing tensions is affecting South Korea's activities to monitor the North.
South Korean media outlets reported that the remarks apparently hint at a partial suspension of the deal.
South Korea's presidential office held a meeting of the National Security Council on Monday. Officials confirmed that the country will step up its defense posture. They also agreed that Seoul will engage in necessary coordination with the United States and Japan.