North and South Korea have withdrawn troops and firearms from 22 front-line guard posts as part of September's agreement to reduce tensions across the world's most fortified border.

The two countries plan to destroy 20 of the structures by the end of November, while symbolically leaving one demilitarized guard post on each side.

South Korea says the military agreement is an important trust-building step that would help stabilize peace and advance reconciliation between the rivals.

But critics say the South risks forfeiting some of its conventional military strength before North Korea has taken any meaningful steps towards denuclearization - an anxiety that is growing as larger nuclear negotiations between Washington and Pyongyang seemingly drift into a stalemate.

South Korean soldiers leave a border guard post at an undisclosed area in the Demilitarized Zone (DMZ). Both North and South Korean militaries withdrew troops and firearms from 22 front-line guard posts on Saturday

South Korean soldiers locking a military gate as they withdraw from a border guard post at an undisclosed area in the Demilitarized Zone (DMZ) dividing the two Koreas

South Korea reportedly has about 60 guard posts stretched across the ironically named Demilitarized Zone, consisting of bunker-like concrete structures surrounded by barbed-wire fences and manned by soldiers equipped with machine guns.

The 155-mile border buffer is peppered with millions of land mines and has been the site of occasional skirmishes between the two forces since the 1950-53 Korean War. The North is believed to have about 160 guard posts within the DMZ.

In the September military agreement, reached on the sidelines of a summit in Pyongyang between North Korean leader Kim Jong Un and South Korean President Moon Jae-in, the Koreas pledged to eventually withdraw all guard posts within the DMZ, but to start by removing 11 from each side as a 'preliminary' measure.

South Korean soldiers saluting before leaving from the Guard Post (GP) on the Demilitarized Zone (DMZ) in Gangwon-do, South Korea, November 6 2018

South Korean soldiers carring military equipment before leaving from the Guard Post (GP). ). The Koreas' military agreement prohibiting hostile activities on ground, sea and air in buffer zones signed during the Pyongyang summit on 19 September between President Moon Jae-in and North Korean leader Kim Jong-un

The South Korean Defense Ministry official said soldiers on Saturday completed the disarming of 11 guard posts on the southern side of the DMZ.

The official, who did not wanted to be named, said the ministry believes the North has also finished withdrawing personnel and weapons from 11 guard posts on the northern side.

The Koreas exchange gifts across the border South Korea airlifted 200 tons of tangerines to North Korea on Monday in return for shipments of pine mushrooms by the North in September. It was a sign that liberal South Korean President Moon Jae-in is pressing on with efforts to improve ties with the North despite stalemated global diplomacy on its nuclear program. A South Korean military transport aircraft is loaded with tangerines bound for North Korea at an airport on Jeju island After a summit meeting between the Koreas in Pyongyang in September, North Korea gave South Korea 2 tons of pine mushrooms - white and brown fungi considered a healthy delicacy in both Koreas and one of the North's most prized regional products. North Korean leader Kim Jong Un also gave Moon a gift of two white Pungsan dogs. On Monday, Moon tweeted that one of the dogs, named Gomi, gave birth to six healthy puppies last Friday. 'Six dogs were added to a gift of two dogs. I cannot help saying it's a big fortune and I hope that South-North ties will be like this,' Moon said. Pungsan is a dog breed native to North Korea and is best known for its loyalty and bravery during hunting. South Korean President Moon Jae-in touches Gomi the white Pungsan dog, a gift from North Korea Advertisement

The Koreas plan to destroy 20 of the structures by the end of November, while symbolically leaving one demilitarized guard post on each side. They plan to jointly verify the results in December.

The September deal also contained an agreement to create buffer zones along their land and sea boundaries and a no-fly zone above the border, which took effect on November 1.

The Koreas and the U.S.-led U.N. Command recently finished removing firearms and troops from a jointly controlled area at the border village of Panmunjom and eventually plan to allow tourists to freely move around there.

The two countries have also been clearing mines from front-line areas and plan to start in April their first-ever joint search for remains of soldiers killed during the Korean War.

While their militaries move ahead with tension-reducing steps, President Moon is otherwise running out of goodwill gestures toward North Korea, which is under heavy U.S.-led sanctions over its nuclear weapons program.

Unless the sanctions are lifted, it would be impossible for Moon to push ahead with his more ambitious plans for engagement, such as reconnecting railways and roads across the border and normalizing operations at a jointly-run factory park.

After a provocative series of nuclear and missile tests North Korea entered talks with the United States and South Korea this year.

The north has since taken measures such as dismantling its nuclear test site and parts of its rocket-engine testing facility.

Now, Pyongyang insists that sanctions should be removed before there is any further progress in negotiations.

Washington, however, says they will remain until the North takes more concrete steps toward the irreversible and verifiable removal of its nuclear weapons.

Analysts say the discord may have caused the last-minute cancellation of a meeting between U.S. Secretary of State Mike Pompeo and his North Korean counterpart, Kim Yong Chol, that had been scheduled for this past Thursday.

The two were due to discuss denuclearization issues and had planned to set up a second summit between Kim Jong Un and President Donald Trump.

South Korean soldiers saluting as they withdraw from a border guard post at an undisclosed area in the Demilitarized Zone (DMZ) - the two Koreas began destroying 20 guard posts along their heavily-fortified frontier on November 11 under a plan to reduce tensions on the border

A military vehicle waits to carry equipment before leaving from the Joint Security Area (JSA) on the Demilitarized Zone (DMZ) in the border village of Panmunjom in Paju, South Korea. The two Koreas agreed to turn the JSA into a weapon-free zone under the agreement signed by their defense chiefs during the Pyongyang summit in September

President Moon, who has met Kim three times this year, believes that better ties between the Koreas will help resolve the nuclear issue.

South Korea's Unification Ministry said Monday it has approved a visit by seven North Koreans to attend an academic forum in the South later this week.

The forum is on regional issues, including Japan's wartime mobilization of laborers in the Asia-Pacific region.