United States President Joe Biden has accused China and Russia of failing to show leadership on addressing climate change.He said was a “big mistake” for his Chinese counterpart, Xi Jinping, to not attend the United Nations Climate Change Conference.Biden’s comments come as the US and China are seeking to improve diplomatic relations amid several points of tension.United States President Joe Biden has accused China and Russia of failing to show leadership on addressing climate change, saying he believes it was a “big mistake” for his Chinese counterpart, Xi Jinping, to not attend the United Nations Climate Change Conference (COP26).Speaking on the sidelines of the summit on Tuesday, Biden said his own presence at the event in Glasgow, Scotland, showed that “America is back” after the “America First” foreign policy approach of former President Donald Trump.“The fact that China is trying to assert, understandably, a new role in the world as a world leader – not showing up, come on!” Biden told reporters before flying out of Glasgow.Biden said: It just is a gigantic issue and they walked away. How do you do that and claim to be able to have any leadership? It’s been a big mistake, quite frankly, for China not showing up. The rest of the world looked at China and said ‘What value are they providing?’Xi, who leads the world’s largest emitter of carbon emissions, has not travelled outside of China since the beginning of the Covid-19 pandemic.Biden’s comments come as the US and China are seeking to improve diplomatic relations amid several points of tension, including concerns in Washington over Beijing’s recent military actions in Taiwan’s air defence zone and China’s human rights record.Beijing, which claims Taiwan as its own territory, has stepped up cross-strait activities this year, with the number of recorded incidents on track to be double the level of 2020.A senior US official said last month that Biden and Xi planned to hold a virtual bilateral meeting before the end of the year amid the tensions.Xi and Biden spoke by phone on September 9 in what the White House said was part of an “ongoing effort to responsibly manage the competition” between the countries.That call ended a nearly seven-month gap in direct communication between the leaders.Biden said on Tuesday that he hoped their talks would bring more predictability in relations. “I’m going to be clear. This is competition; it does not have to be conflict,” he said.”I have also indicated to him – and I’m not reluctant to say it publicly – that we expect him to play by the rules of the road.”Rafe Pomerance, a distinguished senior Arctic policy fellow at the US-based Woodwell Climate Research Centre, said on Tuesday that he was disappointed the Chinese president did not attend the COP26 conference.”I think their [climate change] commitment hasn’t grown significantly,” Pomerance told Al Jazeera about China’s policies.”I think the pressure will build on the Chinese. They are vulnerable to climate change in many regions and have to change course. They’ve got the same problem as many others, in fact worse … so they’re going to have to come around in a bigger way,” he said.Meanwhile, Biden on Tuesday also slammed Russian President Vladimir Putin, who is not attending COP26, on the climate file. Russia is the world’s fourth-largest source of carbon emissions.The US president said:His tundra is burning – literally, the tundra is burning. He has serious, serious climate problems, and he is mum on willingness to do anything.Russia approved a long-term government climate strategy earlier this week targeting carbon neutrality by 2060, however, and it has rejected earlier US allegations it was not doing enough on climate change.”Russia as a country is making enormous efforts and will continue to do so systematically to reduce the anthropogenic burden on the climate, but this is a process that requires adequate measures on the part of all states,” Kremlin spokesperson Dmitry Peskov said on Monday.Putin met Biden in June in Geneva, where they announced that the two nations had agreed to enter into a bilateral dialogue on “strategic stability” aimed at reducing the risks of unintentional conflict and restraining nuclear weapons.This week, CIA Director William Burns is making a rare visit to Moscow to discuss the US-Russia relationship. A US Embassy spokesperson said Burns was leading a delegation of senior US officials to Moscow on Tuesday and Wednesday at Biden’s request.”They are meeting with members of the Russian government to discuss a range of issues in the bilateral relationship,” the spokesperson said.Never miss a story. Choose from our range of newsletters to get the news you want delivered straight to your inbox.