SEOUL - The Republic of Korea has airlifted thousands of boxes of tangerines to the Democratic People's Republic of Korea in return for a large shipment of pine mushrooms from Pyongyang in September, officials said on Monday.

ROK military planes flew to Pyongyang, the DPRK's capital, on Sunday and Monday to deliver the fruit from the southern island of Jeju, according to Seoul's Defense Ministry.

The airlifts are another sign that ROK President Moon Jae-in is moving ahead with efforts to improve ties with the DPRK.

After September's inter-Korean summit in Pyongyang, the DPRK gave the ROK 2 tons of pine mushrooms as a goodwill gesture. Pine mushrooms are large white fungi that are considered a healthy delicacy in Asian countries. They are one of the DPRK's most prized regional products, and the country shipped them to the ROK in 2000 and 2007 after previous summit talks.

After that, DPRK's top leader Kim Jong-un also gave Moon a gift of two dogs, both white Pungsans.

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.

The tangerine delivery is a sign that the two neighbors are pushing ahead with efforts to improve ties despite a stalemate in global diplomacy over Pyongyang's nuclear program.

According to Seoul and Washington officials, Pyongyang recently postponed high-level talks with the United States meant to discuss achieving nuclear disarmament and setting up a second summit between US President Donald Trump and Kim.

After a provocative run of nuclear and missile tests last year, the DPRK entered talks with the US and the ROK this year saying it's willing to deal away its advancing weapons arsenal. It has since taken measures like dismantling its nuclear testing site and parts of its rocket-engine testing facility, but US officials want the country to take more significant and irreversible steps toward denuclearization.

President Moon of the ROK was behind US-DPRK diplomacy and has met Kim three times this year.

The ROK Unification Ministry said on Monday that it has approved a visit by seven DPRK citizens to attend an academic forum in the ROK later this week. The event will center around regional issues, including Japan's wartime mobilization of laborers in the Asia-Pacific region.

AP - Xinhua