The two Koreas opened a second day of general-grade military talks Wednesday at the border village of Panmunjom.

Topping their agenda are each side’s proposal on readjusting the western sea border and signing a military security guarantee agreement for the pilot operation of newly reconnected inter-Korean railways.

In a keynote address Tuesday, the North Korean delegation acknowledged South Korea’s sovereignty over five islands near the Northern Limit Line and proposed to discuss setting the boundary of waters surrounding the islands.

In Tuesday's session, Seoul proposed holding the second inter-Korean defense ministers' talks to discuss eight pending military matters, including the readjustment of the sea border and phased disarmament and related verification.

After attending the opening session in the morning, the North Korean delegation did not return for the scheduled afternoon meeting. Exact reasons for the North's action were not known but observers speculate that Pyongyang delegates may have wanted to consult their government over the South's proposal on the delineation of the maritime border.

North Korea does not recognize the Northern Limit Line set unilaterally by the U.S.-led U.N. forces at the end of the Korean War in 1953. Pyongyang has long insisted that a new border be drawn further south of its coastline on the West Sea. In 1998 and 2002, the navies of the two Koreas fought bloody gun battles in the area that resulted in heavy casualties.

The two Koreas also agreed last week to begin test runs on May 25th of two railways built across the border.

The railways were cut off in 1951, a year after the outbreak of the Korean War. A set of parallel roads have been in use since last year for South Koreans traveling to the North.

The military talks will continue through Thursday at the border truce village of Panmunjom.