A military pact between South Korea, the United States and Japan on sharing and safeguarding sensitive information on North Korea's missile and nuclear programme has gone into effect, the South Korean defence ministry has said.
Under the trilateral pact, finalised on Monday, South Korea and Japan will share intelligence via the US, which has legally-binding bilateral intelligence sharing agreements with each of the Asian countries.
"Military secrets are divided into first, second and third level classified information, but the nation providing the information will decide on the level of classified material," Kim Min-seok, a spokesman for South Korea's defence ministry, said.
The three countries plan to hold further discussions down the road to fine-tune the scope of intelligence sharing to be allowed under the pact, a South Korean defence ministry official was quoted as saying by the Seoul-based Yonhap news agency.
The Pentagon said the deal will advance the security of the three countries.
"In particular, information sharing among the signatories on the nuclear and missile threats posed by North Korea will allow for a more effective response to future provocations and during contingencies."
"The Department of Defense is to serve as the hub for information shared trilaterally. The arrangement does not impose any new legal obligations on the signatories," the Pentagon said in a statement.
Some South Koreans have voiced concerns about signing a security pact with Japan, a one-time colonial ruler. Besides Japan's annexation of Korean peninsula that ended in 1945, bilateral ties have been plagued by a prolonged territorial dispute over a group of tiny islets.
Seoul's previous attempt to sign a military deal with Japan two years ago was shelved after public opposition.
Meanwhile, South Korea proposed on Monday to resume stalled talks with North Korea, hoping to hold negotiations in January to cover issues including reunions for families separated by the 1950-53 Korean war, and possible cooperation projects.
The overture came amid high diplomatic tension as the US, the South's key ally in the region, has blamed the North for a devastating cyberattack on the US-based unit of Japan's Sony Corp - Sony Pictures Entertainment.
North has denied responsibility for the attack and subsequently blamed Washington for its own internet outages.