South Korea, the United States and Japan staged a trilateral missile defense exercise in the international waters of the East Sea on Sunday, Seoul's Navy said, after North Korea's launch of an intercontinental ballistic missile last week.

The drills took place as the three countries have been reinforcing security coordination amid Pyongyang's continued saber-rattling this year, highlighted by the firing of a Hwasong-18 solid-fuel ICBM last Wednesday.

The exercise featured three Aegis-equipped destroyers -- the South's ROKS Yulgok Yi I, the US' USS John Finn and the Japan Maritime Self-Defense Force's JS Maya, according to the armed service.

Under a scenario of a ballistic missile launch by North Korea, the exercise focused on practicing procedures to detect and track a computer-simulated ballistic missile target, and share related information, it said.

"This exercise served as an opportunity to enhance our military's response capabilities against ballistic missiles and improve security cooperation among South Korea, the United States and Japan," a Navy official was quoted as saying.

"Based on our military's powerful response system and trilateral coordination, (we) will effectively respond to North Korea's nuclear and missile threats," the official added.

The three countries last held such a three-way missile defense exercise in April. Sunday's exercise marked the fourth one under the Yoon Suk Yeol administration, which has made efforts to bolster trilateral cooperation against Pyongyang's military threats.

In a show of force against the North's ICBM launch, South Korea and the United States also staged combined air drills Thursday, involving a US B-52H strategic bomber. (Yonhap)