SEOUL, South Korea >> North Korea today blew up some of its front-line guard posts as part of an agreement to ease tensions along its heavily fortified border with South Korea, Seoul’s Defense Ministry said.

In September, the Koreas’ militaries agreed at a leaders’ summit in Pyongyang to eventually dismantle all guard posts inside the 248-kilometer (155-mile) -long, 4-kilometer (2.5-mile) -wide border. They later withdrew weapons and troops from 11 of their guard posts and decided to completely dismantle 10 of them by the end of November.

Seoul’s Defense Ministry said it confirmed the dismantling of 10 North Korean guard posts today. It said North Korean soldiers had used hammers to tear down parts of the guard posts ahead of today’s near-simultaneous demolitions. A ministry statement said North Korea had informed the South of its plans in advance.

The ministry released photos showing parts of structures on what it said was the North Korean side of the central portion of the border, an explosion with black smoke at the site, and debris scattered around the area with no trace left of the structure.

South Korea began dismantling 10 of its guard posts with dynamite and excavators last week. Ministry officials said today that they haven’t completed the dismantling work yet.

The Korean border, the world’s most heavily armed with an estimated 2 million land mines, has been the site of deadly fighting and bloodshed. Called the Demilitarized Zone, it was originally created as a buffer at the end of the 1950-53 Korean War.

South Korea had about 60 posts inside the DMZ guarded by layers of barbed wire and manned by troops with machine guns. North Korea was estimated to have 160 such front-line posts. Once the dismantling is done, the two Koreas are to jointly verify their work by the end of December. They haven’t decided when they will dismantle the rest of the guard posts.

Under the September agreements, the Koreas have also taken steps to disarm the shared border village of Panmunjom, halted live-fire drills along the border and have been removing mines at a front-line area to conduct their first joint searches for Korean War dead.

Relations between the Koreas have improved since North Korean leader Kim Jong Un reached out to South Korea and the United States early this year with a vague promise to achieve the denuclearization of the Korean Peninsula. U.S.-North Korea talks on the North’s nuclear program haven’t produced much progress since Kim and U.S. President Donald Trump held the countries’ first summit in Singapore in June.