China and North Korea pledged greater cooperation in the face of what Pyongyang described as “hostile forces” as the two countries marked the 60th anniversary of their defence treaty on Sunday. North Korean leader Kim Jong-un said the two countries were “staunchly advancing towards a bright future by smashing the high-handedness and desperate manoeuvres of hostile forces”, according to a statement from Pyongyang’s Ministry of Foreign Affairs. Chinese President Xi Jinping took a less combative tone, saying the “brotherhood” between the two countries had contributed to “regional peace and world peace”. Xi said the world was “undergoing profound changes unseen in a century”, a phrase he has repeatedly used in speeches. In a top-level cadres meeting in January, he said he believed “ time and momentum are on China’s side ”, despite challenges including the coronavirus pandemic , supply chain disruptions, deteriorating relations with the West and a slowing economy. “I hope to strengthen strategic communications with [Kim] so our bilateral relations can be developed forward in the correct direction, and the friendly cooperation between us will be able to excel to new levels, and benefit our countries and our people ,” Xi said, according to the Chinese foreign ministry. “China is determined in supporting North Korea’s economic development and improvements to people’s livelihoods.” China and North Korea are grappling with uncertainty in their relationship with the United States under the administration of US President Joe Biden , and facing greater isolation from strict border closures to contain the coronavirus pandemic. Beijing is also under pressure from the US and its allies on issues ranging from trade to human rights. And Pyongyang has accused Biden of pursuing a “hostile policy” by saying he will deal with the threat posed by North Korea’s nuclear programme “through diplomacy as well as stern deterrence”. Kim said last month that Pyongyang was ready for both “dialogue and confrontation ” with the US. Under the two countries’ 1961 treaty of friendship, cooperation and mutual assistance, North Korea and China have committed to offering each other immediate military support and other aid in the event of an attack. The Chinese foreign ministry said on Wednesday that the treaty would “always be valid” unless the two sides agreed to end it. Beyond the two countries’ security ties, China also accounts for about 90 per cent of North Korea’s trade and has repeatedly voiced support at the United Nations’ Security Council for easing sanctions on Pyongyang.