SEOUL--South Korea informed Japan on Nov. 22 that it would extend the General Security of Military Information Agreement (GSOMIA) designed to share highly classified military intelligence, sources said.

The notification came just hours before the agreement was to have expired at midnight.

Seoul told Tokyo on Aug. 23 that it planned to let GSOMIA expire after Japan tightened its export control measures on high-tech products to South Korea. Tokyo’s move followed South Korean Supreme Court rulings from last year ordering Japanese companies to pay compensation to wartime Korean laborers.

But U.S. government officials made a concerted effort to persuade their South Korean counterparts to change their minds, given the importance of GSOMIA for defense cooperation in the Far East, especially in light of North Korea’s continued development of ballistic missiles and nuclear weapons.

South Korea had insisted that it would not extend GSOMIA unless Japan reviewed its stiffer export control measures.

The abrupt change in course at the last minute likely reflects the strong pressure exerted by Washington, which considers GSOMIA a key component of defense cooperation with Tokyo and Seoul.