Leaders of the G7 nations began arriving in France on Saturday for a summit as a US-China row over protectionism highlighted President Emmanuel Macron's tough task in delivering real results on trade, Iran and climate change.
The three-day meeting in the Atlantic seaside resort of Biarritz takes place amid sharp differences over a clutch of global issues that risk further dividing a group of countries already struggling to speak with one voice.
Summit host Mr Macron wants the leaders of Britain, Canada, Germany, Italy, Japan and the United States to focus on the defence of democracy, gender equality, education and climate change, and has invited leaders from Asia, Africa and Latin America to join them for a global push on these issues.
But with the trade war between China and the United States worsening, European governments struggling to defuse tensions between Washington and Tehran and global condemnation growing over illegal fires in the Amazon, his agenda could be eclipsed.
US President Donald Trump's history of pugnacity at multilateral gatherings, which brought last year's G7 summit to an acrimonious conclusion, means there is scant hope for substantive agreements.
Mr Macron was exploring holding a joint news conference with Trump at the summit's close, a French diplomatic source said, but has already decided that, to avoid another failure, there will be no final communique.
"French President Emmanuel Macron... bills the meeting as a chance to relaunch multilateralism, promote democracy and tame globalisation to ensure it works for everyone," Stewart Patrick of the Council on Foreign Relations think tank wrote.
"More likely, the gathering will expose the political, economic and ideological fault lines threatening Western solidarity and international cooperation."
Mr Trump's fireworks at the Charlevoix summit in Canada last year prompted foreign policy analysts to dub the Group of Seven nations the G6+1.
US officials said Mr Trump would tout his policies of tax cuts and deregulation and press allies to follow his example to stave off problems with the global economy.
Hours before leaving for Biarritz, Mr Trump reacted angrily to China's move to impose retaliatory tariffs on more US goods, even saying he was ordering US companies to look at ways to close their operations in China. The president cannot legally compel US firms to abandon China immediately.
Mr Trump also took aim at France's new tax on big tech companies, threatening to tax French wine "like they've never seen before". His remarks cast doubts over Mr Macron's chances to secure agreement at the summit on a universal digital tax.
China's President Xi Jinping is not among the Asian leaders invited to the Biarritz summit.
Adding to the unpredictable dynamic between the G7 leaders are the new realities facing Brexit-bound Britain: dwindling influence in Europe and growing dependency on the United States.
New Prime Minister Boris Johnson will want to strike a balance between not alienating Britain's European allies and not irritating Trump and possibly jeopardising future trade ties. Messrs Johnson and Trump will hold bilateral talks on Sunday morning.
Even so, diplomats played down the likelihood of Messrs Trump and Johnson joining hands against the rest, citing Britain's close foreign policy alignment with Europe on issues from Iran and trade to climate change.
"There won't be a G5+2," one senior G7 diplomat said.
Mr Johnson said ahead of the summit that Britain would not retreat from its responsibilities on the world stage after Brexit, nor sacrifice its belief in the global order.
The remarks were a riposte to those who say leaving the European Union will diminish Britain's influence on the global stage and force a pivot towards Mr Trump's unorthodox and often confrontational approach to diplomacy.
Anti-G7 demonstrators are due to protest in Hendaye on the nearby French-Spanish border but will be kept away from Biarritz by more than 13,000 police officers, backed by soldiers.
EU leaders on Friday piled pressure on Brazilian President Jair Bolsonaro over fires raging in the Amazon rainforest.
Mr Macron said Mr Bolsonaro had lied in playing down concerns about climate change at a G20 summit in Japan in June, and threatened to veto a trade pact between the European Union and the Mercosur bloc of South American countries.
A French diplomatic source said advisers to the G7 leaders were working on concrete initiatives to respond to the fires.
"Our house is burning. Literally. The Amazon rain forest – the lungs which produce 20 percent of our planet's oxygen – is on fire," Mr Macron tweeted in the run-up to the summit.
Britain joined Germany on Saturday in criticising Mr Macron's decision to block the EU-Mercosur trade deal.
"There are all sorts of people who will take any excuse at all to interfere with trade and to frustrate trade deals and I don't want to see that," Prime Minister Johnson told reporters.
The president of the European Council on Saturday rebuffed Mr Trump's suggestion that Russia be readmitted to the G7, saying there were even more reasons than before for keeping Moscow out.
The US president has said it would be "appropriate" to have Russia rejoin what used to be the G8, which Russia was excluded from in 2014 after it annexed Ukraine's Crimea and then backed an anti-Kiev rebellion in the industrial region of Donbas in eastern Ukraine.
"One year ago, in Canada, President Trump suggested reinviting Russia to G7, stating openly that Crimea's annexation by Russia was partially justified. And that we should accept this fact," said Donald Tusk who, as president of the European Council, represents the EU's 28 member states.
"Under no condition can we agree with this logic," he added.
Earlier this week Germany, France and Britain also rejected the idea of inviting Russia back into the group.