A special envoy from Kim Jong-un, the top leader of the Democratic People's Republic of Korea, delivered a handwritten letter from Kim to President Xi Jinping on Friday.

The envoy said that peace on the Korean Peninsula and in Northeast Asia is not guaranteed due to the complex situation, but his country is willing to "take positive actions" to solve problems through dialogue.

Experts said that by complaining there is no security guarantee, Pyongyang is not threatening but expressing concerns and seeking support. They also said the meeting with Xi showed that talks between Beijing and Pyongyang in the past two days have yielded progress to some degree.

The Director of the Korean People's Army's General Political Bureau, Choe Ryong-hae, passed on the letter to Xi when they met at the Great Hall of the People.

The Chinese side confirmed the letter after the meeting but gave no details of its contents.

Choe is the first special envoy Kim has sent to China after taking office as top leader of the DPRK in late 2011.

Xi told Choe that the denuclearization of the peninsula was an aspiration of all peoples and an inevitable trend, saying problems should be resolved through talks.

"China hopes all sides exercise calm and restraint, push for a lessening of tensions, restart the Six-Party Talks process and make unremitting efforts ... for long-lasting peace and stability," Xi said.

Choe, a member of the Presidium of the Political Bureau of the Workers' Party of Korea Central Committee said: "The DPRK is willing to make joint efforts with all parties to appropriately resolve related issues through multilateral dialogue and consultations like the Six-Party Talks, and maintain peace and stability on the peninsula.

"To this end, the DPRK is willing to take positive actions," he added.

The Six-Party Talks, initiated in 2003 in response to Pyongyang withdrawing from the Nuclear Non-Proliferation Treaty, involve the DPRK, the Republic of Korea, China, the United States, Japan and Russia.

In April 2009, the DPRK, angered by a UN Security Council resolution to impose more sanctions on Pyongyang for a nuclear test, left the talks and resumed its nuclear-weapons program.

Choe also met Fan Changlong, vice-chairman of the Central Military Commission, earlier on Friday.

Fan said tensions on the Korean Peninsula regarding the nuclear issue have intensified strategic conflicts among involved parties.

According to a statement issued by the People's Liberation Army after the meeting, Choe said: "Conditions on the Korean Peninsula and in the East Asian region are complex and exceptional, and there is no guarantee of peace. The DPRK people require a peaceful and stable environment to build their nation."

Choe arrived in Beijing on Wednesday, accompanied by senior military and ruling-party officials.

He has met Liu Yunshan, a member of the Standing Committee of the Political Bureau of the Central Committee of the Chinese Communist Party, and Wang Jiarui, head of the International Department of the CPC Central Committee.

Chen Qi, an expert on East Asian studies at Tsinghua University, said the arrangement of the meeting between Xi and Choe means the two sides have reached agreement to some degree and deepened their mutual understanding through the previous three rounds of meetings with Wang Jiarui, Liu Yunshan and Fan Changlong.

The meeting with Xi also showed that Choe was treated with utmost courtesy in Beijing, Chen said.

He added there is no need to over-analyze Choe's remarks of "no guarantee of peace" or view it as threatening.

"It's normal conversation between high-ranking military officials," he said.

Chen said the visit was a very successful one for Choe, and might pave the way for future bilateral leaders' meetings or working-level conferences.

Choe's tour to China has attracted close attention from media in both the West and East Asia, with almost every arrangement fully analyzed by media.

The Seoul-based Aju Business Daily said that by sending the envoy, Pyongyang has sent a positive signal.

"As China attaches great importance to peace and stability on the Korean Peninsula, Pyongyang is highly likely to promise China that it may restrain behavior such as missile launches," the paper said.