SEOUL, April 22 (CGTN) - Pyongyang and Seoul on Friday both confirmed an exchange of letters between Kim Jong Un, the leader of the Democratic People's Republic of Korea (DPRK) and the outgoing Republic of Korea (ROK) President Moon Jae-in earlier in the week.

The exchange of letters came against a backdrop of strained cross-border ties since a failed DPRK-U.S. summit in 2019, and flaring tension after Pyongyang launched intercontinental ballistic missiles (ICBMs) last month.

DPRK's state media Korean Central News Agency (KCNA) said Kim received a "personal" letter from Moon on Wednesday and sent a reply letter the next day, thanking Moon for trying to improve inter-Korean relations.

According to KCNA, Kim told Moon that their "historic" summits gave the people "hope for the future", and the two agreed that ties would develop if both sides "make tireless efforts with hope."

"Kim Jong Un appreciated the pains and effort taken by Moon Jae-in for the great cause of the nation until the last days of his term of office," KCNA said, adding the exchange of letters was an "expression of their deep trust."

KCNA also noted Moon and Kim held the same view that inter-Korean relations would "improve and develop" if the two sides continue to strive toward that goal.

Moon's office also confirmed that he had exchanged "letters of friendship" with Kim. Presidential spokesperson Park Kyung-mee said Cheong Wa Dae plans to brief the media on the letters.

Moon staked his legacy on improving inter-Korean ties and helped arrange unprecedented meetings between Kim and then-U.S. President Donald Trump in 2018 and 2019.

Moon and Kim held three summits in 2018, agreeing to completely denuclearize the Korean Peninsula, permanently achieve peace on the peninsula, stop all hostile acts near the inter-Korean border and increase exchange and cooperation.

However the inter-Korean ties have been stalled since the second summit between Kim and Trump ended without agreement in February 2019 at the Vietnamese capital of Hanoi.