North Korea and China have reportedly signed an agreement on bilateral cooperation in security.

North Korea’s official Korean Central News Agency (KCNA) said that Chinese Minister of Public Security Meng Jianzhu signed the agreement with North Korea’s Minister of People’s Security Ju Sang-song on Sunday during a visit by Meng to North Korea.

But the North Korean news outlet did not elaborate on the details of the agreement.

South Korean sources say that the agreement likely deals with the issue of border security --- specifically the issue of North Koreans fleeing to China.

KCNA said that the Chinese Ministry of Public Security delivered “cooperation goods” to the North Korean Ministry of People’s Security during a ceremony held in Pyongyang on Sunday. But the details of the delivery were not revealed.