It's allegedly the first test of such weaponry by Pyongyang since January
North Korea fired two cruise missiles off its west coast into the Yellow Sea early on Wednesday, a South Korean military source told Yonhap news agency.
The alleged missile test coincided with a press conference by South Korean President Yoon Suk-yeol, marking 100 days since he took office.
It also came a day after South Korean and US troops launched preliminary drills ahead of the upcoming annual Ulchi Freedom Shield (UFS) wargames.
Pyongyang has repeatedly criticised joint military manoeuvers between Seoul and Washington, branding them provocative, and claiming they only increase tensions on the Korean Peninsula.
North Korea is banned from launching ballistic missiles under UN Security Council resolutions, but the sanctions don't cover cruise missiles.
According to Yonhap, Pyongyang last test-fired cruise missiles in January.