The Joint Chiefs of Staff(JCS) said on Monday that North Korea fired two short-range ballistic missiles toward the East Sea earlier in the day.

The JCS said it detected the missiles launched from Chunghwa County, North Hwanghae Province from 7:47 a.m.

The missiles, presumed to be KN-23 types modeled after Russia's Iskander ballistic missile, flew about 370 kilometers. South Korean and U.S. intelligence authorities are working on analyzing the details of the launches.

The latest missile launch comes four days after the regime claimed to have carried out what it dubbed a “nuclear-capable underwater drone test.”

It also marks eight days after the North fired a short-range ballistic missile toward the East Sea from the Tongchang-ri area in North Pyongan Province on the country’s west coast, which the regime said was part of a nuclear warhead midair explosion test.

The JCS said that the military has strengthened surveillance and vigilance in preparation for additional launches, maintaining a full readiness posture in close cooperation with the United States.

Marking the eighth ballistic missile launch this year, the latest North Korean provocation appears to be a show of force against the ongoing “Ssangyong” joint amphibious training between South Korea and the U.S.

A nuclear-powered U.S. aircraft carrier, the USS Nimitz, is also scheduled to be dispatched to the Korean Peninsula later this week to participate in a naval drill set to be held in the East Sea.