Image via NATO/Flickr/CC BY-NC-ND 2.0

BRUSSELS  Leaders of the North Atlantic Treaty Organization (NATO) hope to open a new chapter in transatlantic relations at a summit with US President Joseph R. Biden, Jr., on Monday, agreeing to focus on tackling climate change for the first time as well as facing up Chinas military rise. 

Described as a pivotal moment by NATO Secretary-General Jens Stoltenberg, the summit aims to turn the page on four tense years with Mr. Bidens predecessor Donald J. Trump, who shook confidence in the Western alliance by calling it obsolete. 

For the 30 allies meeting in Brussels, diplomats say nothing could be further from the truth, looking to the nuclear-armed alliance founded in 1949 to help deal with threats from extreme weather that can worsen conflicts to Russian attempts to undermine Western democracies through covert attacks. 

NATO owes it to the billion people we keep safe every day to continually adapt and evolve to meet new challenges and face down emerging threats, British Prime Minister Boris Johnson, who hosted Mr. Biden and other G7 leaders in Cornwall, England, said in prepared remarks on the Brussels summit eve. 

Russias efforts to divide the West are likely to run through discussions, diplomats said, ahead of a meeting between Biden and Russian President Vladimir Putin on Tuesday in Geneva. 

Since Russias 2014 annexation of Crimea, NATO has modernized its defenses but remains vulnerable to cyberattacks and disinformation, although Moscow denies any attempts to destabilize NATO allies. 

Cyber threats can emerge at any point during a crisis and trigger misunderstandings and unintended signals … that could precipitate war, the European Leadership Network (ELN) research group said in a paper released for the summit. 

But foremost in leaders minds, diplomats say, is a need to hear Mr. Biden recommit the United States to NATO’s collective defense after the Trump era. Mr. Trumps confrontational rhetoric towards allies from 2017 to 2019 at NATO summits created an impression of crisis, envoys said. 

Chinas growing military and economic presence in the Atlantic, including joint military drills with Russia, will prompt a strong response from leaders. A pledge to make NATO militaries carbon-neutral by 2050 is also expected. 

G7 leaders agreed on Sunday to raise their contributions to meet a spending pledge of $100 billion a year by rich countries to help poorer countries cut carbon emissions and cope with global warming.  Robin Emmott/Reuters