SEOUL - The Democratic People's Republic of Korea (DPRK) on Monday test-fired three ballistic missiles into eastern waters ahead of the country's National Day, the Republic of Korea (ROK)'s defense ministry said.

A defense ministry official said that the missiles were launched into the East Sea at about 12:14 pm local time from its western areas near Hwangju county in North Hwanghae province.

Those missiles, which are believed to have been Rodong mid-range missiles with a range of 1,000 km to 1,200 km, traveled about 1,000 km toward Japan.

Yonhap news agency reported that those missiles landed in Japan's air defense identification zone. The DPRK hadn't issued a navigation warning before the test-firings, according to ROK's Joint Chiefs of Staff (JCS).

Seoul's military authorities had already detected preparations for Pyongyang's ballistic missile launches, according to the Yonhap report.

Concerns emerged about possible DPRK provocations ahead of the 68th anniversary on Friday of the founding of the state. In 2014, Pyongyang conducted two rounds of short-range missile launches before the National Day.