The military chiefs of the United States and South Korea spoke over the phone on Tuesday and recognized that North Korea could "conduct provocative actions" in response to large-scale joint drills between the two countries, Reuters reported.
"The chairmen recognized the possibility that North Korea could conduct provocative actions during the Key Resolve/Foal Eagle exercise, or in connection with North Korean major political events in April," a statement from Chairman of the U.S. Joint Chiefs of Staff General Joseph Dunford's office said.
The statement said the two military leaders "discussed response options" during a call that lasted about 30 minutes.
Earlier this month North Korea fired four ballistic missiles into the sea off Japan in response to annual U.S.-South Korea military drills, which the North sees as preparation for war.
South Korean and U.S. troops began the large-scale joint drills, which are billed as defensive in nature, on March 1.
The exercise last year involved about 17,000 American troops and more than 300,000 South Koreans. South Korea has said this year's exercise would be of a similar scale.
The United States has also started to deploy "Gray Eagle" attack drones to South Korea.
"The combined defense posture is firm regardless of the political situation in Korea," the statement quoted Dunford as saying.
South Korea's Constitutional Court removed former President Park Geun-hye from office last week over a graft scandal involving the country's conglomerates at a time of rising tensions with North Korea and China.