South Korea says its intelligence-sharing agreement with Japan has taken effect after the two countries signed the pact to better monitor North Korea.

South Korea and Japan had so far exchanged military intelligence via the United States under a trilateral agreement signed in 2014. But the two Asian neighbors had no direct intelligence-sharing system largely because of disputes stemming from Japan's colonial rule of the Korean Peninsula from 1910 to 1945.

South Korea's defense minister and Japan's ambassador in Seoul signed the deal Wednesday. Seoul's Foreign Ministry says the pact has taken effect.

Worries about North Korea's weapons programs have grown after North Korea conducted its fifth and most powerful atomic bomb test in September.