North Korea launched a ballistic missile Thursday toward its eastern waters, Yonhap News Agency reported citing a South Korean military official.

This comes just two days after North Korea fired an intermediate-range missile over Japan for the first time in five years. “While strengthening our monitoring and vigilance, our military is maintaining a full readiness posture in close cooperation with the United States,” the JCS said in a statement, reported Yonhap News Agency.

The Joint Chiefs of Staff (JCS) said it detected the launches from the Samsok area in Pyongyang between 6:01 am and 6:23 am (local time). It did not provide other details.

The US and South Korea launched four missiles off the east coast of the Korean Peninsula on Wednesday morning, in response to North Korea’s provocative test launch of a ballistic missile over Japan.

This test was the allies’ second exercise within 24 hours, following North Korea’s launch of a ballistic missile over Japan on Tuesday morning, CNN reported.

Earlier, on Tuesday, the US and South Korea initially responded to the launch with a precision bombing exercise, which involved a South Korean F-15K fighter jet firing two air-to-surface munitions at a virtual target in a firing range west of the Korean Peninsula, per the South Korean joint chiefs.

“Through the combined flight of the air strike package and precision strike drills, South Korea and the United States demonstrated their will to respond sternly to any Northern threats as well as their capabilities to conduct a precision strike at the origin of provocations based on the alliance’s overwhelming forces,” the JCS said in a press release.

The allies typically respond to missile tests by North Korea with military exercises, according to CNN.

Meanwhile, Tuesday’s missile launch was the first such missile launch in years, prompting a warning for residents to take cover in northern Japan.

Last week, North Korea fired missiles in an apparent protest against joint naval drills involving the United States and South Korea. Under the Kim Jong-un regime, North Korea this year has tested a record number of missiles as it expands its weapons arsenal.