SEOUL, Korea, Republic Of - The leaders of China and North Korea are reaffirming their traditional alliance following contentious talks between top diplomats from Washington and Beijing and diplomatic isolation and economic problems in the North that have left it ever-more dependent on the Chinese.

The North's official Korean Central News Agency said Tuesday leader Kim Jong Un called for stronger “unity and co-operation” with China in the face of challenges posed by “hostile forces” while exchanging messages with Chinese President Xi Jinping.

According to KCNA and China's Xinhua news agency, Xi in his own message to Kim described bilateral relations as a “valuable asset” to both countries and vowed to make unspecified contributions to the peace and stability on the Korean Peninsula.

KCNA said Xi also expressed a commitment to “provide the peoples of the two countries with better life.” Some analysts saw this as an indication that China would soon provide North Korea with badly needed food, fertilizer and other aid that had been significantly reduced amid the pandemic border closures.

Xinhua said the leaders' messages were exchanged during a meeting between Chinese senior diplomat Song Tao and North Korean Ambassador to China Ri Ryong Nam during a meeting in Beijing on Monday.

The exchange between the leaders came as the Biden administration steps up diplomatic efforts to strengthen co-operation with Asian allies South Korea and Japan to deal with the North Korean nuclear threat and China's growing regional influence.

Top U.S. and Chinese officials traded sharp and unusually public barbs in Alaska last week in their first face-to-face meetings since President Joe Biden took office, where Secretary of State Antony Blinken said Washington is united with its allies in pushing back against Chinese authoritarianism.

The contentious talks in Anchorage came after Blinken and Defence Secretary Lloyd Austin travelled to Japan and South Korea for talks that mainly focused on North Korea and China.

During his visit to Seoul, Blinken sternly criticized North Korea's nuclear ambitions and human rights record and pressed China to use its “tremendous influence” to convince the North to denuclearize.

The North has so far ignored Biden's administration's efforts to reach out, saying it won't engage in meaningful talks with the United States unless Washington abandons what Pyongyang sees as “hostile” policies, which clearly refers to the U.S.-led sanctions and pressure over its nuclear program.

KCNA said Kim addressed the state of the North's relations with the United States and South Korea and said communication between him and Xi was required in the face of changed “external situations and reality,” apparently referring to the new U.S. administration.

Kim's message “stressed the need to strengthen the unity and co-operation between the two parties and two countries to cope with the hostile forces' all-round challenges and obstructive moves,” KCNA said.

As North Korea pursued diplomacy with the U.S. starting in 2018, it also worked to strengthen relations with China, its traditional ally and economic lifeline. But Kim has nothing to show for his ambitious summits with then-President Trump, which collapsed in 2019 over disagreements in exchanging the release of crippling U.S.-led sanctions against North Korea and the North's disarmament steps.

The North's economic woes have been compounded by pandemic border closures and devastating natural disasters that wiped out crops last summer. At a ruling party congress in January, Kim vowed to further expand the North's nuclear program and urged his people to be resilient in the struggle for economic self-reliance.

South Korea's spy agency told lawmakers late last year that North Korea's trade volume with China fell by 75% during the first 10 months of 2020. That led to a shortage of raw materials that plunged the North's factory operation rate to its lowest level since Kim took power in late 2011, and a four-fold price increase of imported foods like sugar and seasonings, according to lawmakers who summarized the agency's closed-door briefing to reporters.

In response to Blinken's comments about China's role in pressing the North to denuclearize, Chinese Foreign Ministry spokesperson Zhao Lijian said China advocates a “two-track approach” to the issue, whereby the U.S. would offer security guarantees to North Korea in exchange for Pyongyang abandoning its nuclear weapons programs.