SEOUL, South Korea (AP) — North Korea has notified rival South Korea that it plans a live-fire drill near the countries’ disputed western sea boundary.

South Korean Defense Ministry spokesman Kim Min-seok said Tuesday that military officials will closely monitor the drills.

Both Koreas regularly conduct artillery drills in the Yellow Sea. North Korea disputes the so-called Northern Limit Line drawn close to its shores at the end of the 1950-53 Korean War. North Korea says it should run farther south.

Ill-will has steadily risen between the rivals after a period of easing tensions earlier this year that saw emotional family reunions of war-divided Koreans.

South Korea fired artillery shells into the North’s waters last month after North Korean shells from a live-fire drill landed south of the NLL.