South Korea's military is assessing Tuesday's launches to determine the nature of the projectiles.
Such a launch would be its fifth missile test of the year, as North Korean leader Kim Jong-un has vowed to bolster the military with cutting-edge technology at a time when talks with South Korea and the United States have stalled.
The isolated nation's biggest cluster of missile launches since at least 2019 has prompted an expression of concern from the UN secretary-general, and the Biden administration has applied new sanctions.
Lee Sang-min, a military expert at the Korea Institute for Defence Analyses say the missile volleys this month look to be aimed at building geopolitical tensions and perhaps push the Biden administration to come up with a new strategy toward North Korean leader Kim Jong-un.
"Cruise missiles are slower than ballistic missiles and so are regarded as less of a threat, but they hit targets with high precision, something North Korea would continue to develop," Lee said.
Cruise missile launches by the North are not banned under United Nations sanctions imposed on Pyongyang, which has defied international condemnation and conducted four rounds of ballistic missile tests, the most recent on January 17.
China and Russia have pushed the UN Security Council to remove a ban on Pyongyang's exports of statues, seafood and textiles, and raise a refined petroleum imports cap.
North Korea has said it is open to talks, but only if the United States and others drop "hostile policies" such as sanctions and military drills.
