A TV cameraman films U.S. aircraft carrier USS Ronald Reagan entering port in Busan, Korea, Sept. 23. AP

A U.S. aircraft carrier returned to the waters east of South Korea on Wednesday to join a trilateral exercise with South Korea and Japan, Seoul officials said, in a show of force following North Korea's ballistic missile launch earlier this week.

The USS Ronald Reagan aircraft carrier left the waters last week after it engaged in a bilateral naval exercise with South Korea and then a trilateral one also involving Japan.

Its redeployment came after Pyongyang fired an intermediate-range ballistic missile (IRBM) over Japan on Tuesday, its first IRBM launch in eight months.

South Korea's Joint Chiefs of Staff (JCS) said the redeployment of a carrier strike group is "very rare" and it demonstrates the "resolve of the South Korea-U.S. alliance to respond sternly to any North Korean provocations and threats."