President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE on Saturday arrived for the annual Group of Seven (G-7) economic summit in France amid major differences among world leaders over issues such as trade, climate change and the situation with Iran.

Trump's past disputes with leaders attending this weekend's summit were in full focus as he arrived in the seaside town of Biarritz, with multiple global delegations emphasizing a push for unity heading into the weekend of discussions.

The president held a working lunch with his French counterpart Emmanuel Macron Emmanuel Jean-Michel MacronNavalny released from hospital after suspected poisoning US-China tensions shadow United Nations meeting The US is missing an opportunity in Lebanon MORE shortly after arriving on Saturday. Macron, the host of this year's summit, has called for leaders to put a focus on climate change and other issues this weekend.

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“We have to work very hard because I see we do share the same objectives,” Macron said during the luncheon. “Thanks again, Mr. President, for taking the time being here and being a partner.”

Trump emphasized in brief remarks that the U.S. and France have "been friends for a long time."

"We have a very good relationship — sort of, I think I can say, a special relationship," he said, adding, "I think we'll accomplish a lot this weekend."

This year’s summit comes as Trump ramps up his "America First" policy approach on a slate of pressing issues, often to the chagrin of European allies and other nations in the G-7 who favor a more collective approach.

Several European figures on Saturday spoke out against the Trump administration's widening trade war with China after Washington's announcement the previous day that it would raise tariffs on hundreds of billions of dollars in Chinese goods following new tariffs unveiled by Beijing earlier in the day.

British Prime Minister Boris Johnson said he planned to urge Trump to ease tensions with China when the pair sit down for a breakfast on Sunday morning. European Council President Donald Tusk also slammed what he called “senseless disputes” on trade between Trump and other global leaders.

“For me, it’s absolutely clear that if someone, for example ... the United States and President Trump, uses tariffs and taxation as a political instrument, tool for some different political reasons, it means that this confrontation can be really risky for the whole world, including the EU,” Tusk told reporters.

Trump has long been known to shy away from diplomatic norms when attending major heads-of-state meetings, and he cut short his trip to last year's G-7 summit in Canada amid personal feuds with several other leaders in attendance at the event.

The president excoriated Canadian Prime Minister Justin Trudeau as “meek and mild” and “dishonest & weak” during their conversations on trade at last year’s summit, and he threatened to withhold the United States’s signature from a joint communique then.

This year's summit is expected to end without attendees signing a joint communique, something Macron signaled before the summit began. But various political figures and critics of Trump have argued that it is still important for leaders to offer a message of unity.

"As president, @BarackObama used these summits as means of coordinating a joint response to the global financial crisis. The contrast is stark," former Obama senior adviser David Axelrod David AxelrodThe Memo: Warning signs flash for Trump on debates GOP hunts for leverage in revived COVID-19 talks Pelosi says there shouldn't be any debates between Biden and Trump MORE tweeted Saturday.

While this weekend's events is sure to include its share of ceremonial flair, leaders will be gathering amid sharp contrasts over various U.S. and European policies that have put a strain on trans-Atlantic relationships over the past year.

Trump has needled Macron over his 2018 comments when he pushed for a "true, European army," highlighting the potential threat of Russia and saying that the continent needed “to defend itself better alone,” and he has gone after German Chancellor Angela Merkel over trade and a Russian oil pipeline.

Before departing the White House on Friday night for the trip to France, Trump renewed his threat to slap tariffs on French wine after Macron signed a digital services tax on tech companies making at least 750 million euros annually, something that would affect U.S.-based tech giants such as Apple, Google, Facebook and Amazon.

"Those are great American companies, and frankly I don’t want France going out and taxing our companies," Trump said. "And if they do that ... we’ll be taxing their wine like they’ve never seen before."

That prompted a warning from the EU's Tusk: "The EU stands by France. If the U.S. imposes tariffs on France, the EU will respond in kind."

Other issues sure to showcase differences between those gathered this weekend include climate change and the international strategy on dealing with Iran.

Trump has ratcheted up his rhetoric against Iran over its military activities and uranium enrichment, slapping sanctions on its government in the hopes of pressuring it to the negotiating table. In the meantime, European heads of state are scrambling to persuade Tehran to abide by the Obama-era nuclear pact, the same deal from which Trump withdrew the U.S. last year and continues to deride.

A French diplomat told The Associated Press that Macron used the working lunch with Trump on Saturday to outline a French plan aimed at easing tensions with Iran, saying France has been working on the plan for weeks.

Macron, who is setting the agenda for this year’s summit as its host, has also called on leaders to discuss and take further action to tackle climate change, specifically pointing to fires that are ripping through the Amazon.

Trump, who famously withdrew the U.S. from the Paris climate accord, has cast doubt on the veracity of climate change itself and has a relationship with Brazilian leader Jair Bolsonaro, whose policies some claim have exacerbated the blazes.

The ongoing tensions appeared close to boiling over Saturday, when Tusk took Trump to task over his trade policies, saying, “This may be the last moment to restore our political community.”