NEW YORK (AP) — President Joe Biden planned to use his first address before the U.N. General Assembly to reassure other nations of American leadership on the global stage and call on allies to move quickly and cooperatively to address the festering issues of the COVID-19 pandemic, climate change and human rights abuses.

Biden, who arrived in New York on Monday evening to meet with Secretary-General Antonio Guterres ahead of Tuesday's address, offered a full-throated endorsement of the body's relevance and ambition at a difficult moment in history.

The president, in brief remarks at the start of his meeting with Guterres, returned to his mantra that "America is back" — a phrase that's become presidential shorthand meant to encapsulate his promise to take a dramatically different tack with allies than predecessor Donald Trump.

"The vision of the United Nations has never been short on ambition, any more than our Constitution," Biden said.

But the president was facing a healthy measure of skepticism from allies during his week of high-level diplomacy. The opening months of his presidency have included a series of difficult moments with friendly nations that were expecting greater cooperation from Biden following four years of Trump's "America first" approach to foreign policy.

Eight months into his presidency, Biden has been out of sync with allies on the chaotic ending to the U.S. war in Afghanistan. He has faced differences over how to go about sharing coronavirus vaccines with the developing world and over pandemic travel restrictions. And there are questions about the best way to respond to military and economic moves by China.

Biden also finds himself in the midst of a fresh diplomatic spat with France, the United States' oldest ally, after announcing plans — along with Britain — to equip Australia with nuclear-powered submarines. The move is expected to give Australia improved capabilities to patrol the Pacific amid growing concern about the Chinese military's increasingly aggressive tactics, but it upended a French defense contract worth at least $66 billion to sell diesel-powered submarines to Australia.

French Foreign Minister Jean-Yves Le Drian said Monday there was a "crisis of trust" with the U.S. as a result of the episode.

Before Biden's arrival, EU Council President Charles Michel strongly criticized the Biden administration for leaving Europe "out of the game in the Indo-Pacific region" and ignoring the underlying elements of the trans-Atlantic alliance — transparency and loyalty — in the withdrawal from Afghanistan and the announcement of the U.S.-U.K.-Australia alliance.

Despite such differences, Biden hoped to use his address to the General Assembly as well as a series of one-on-one and larger meetings with world leaders this week to make the case for American leadership on the world stage.

"There are points of disagreement, including when we have disagreed with the decisions other countries are making, the decision points of when countries have disagreed with the decisions we're making," White House press secretary Jen Psaki said. "But the larger point here ... is that we are committed to those alliances, and that always requires work from every president, from every global leader."

In an interview before his meeting with Biden, Guterres told The Associated Press that he was concerned about the "completely dysfunctional" U.S.-China relationship and that it could lead to a new cold war. Psaki said the administration disagreed with the assessment, adding that the U.S.-China relationship was "one not of conflict but of competition."

In his address Tuesday, Biden planned to put a heavy emphasis on the need for world leaders to work together on the COVID-19 pandemic, meet past obligations to address climate change, head off emerging technology issues and firm up trade rules, White House officials said.

Biden was expected to release new plans to assist the global vaccination effort and to talk about the U.S. plan to meet its part of financial commitments that the U.S. and other developed nations made in 2009 to help poorer nations adopt clean energy technology, assistance that was due to kick in annually last year, according to a senior administration official who spoke on the condition of anonymity to preview the president's remarks.

Ahead of his departure, the Biden administration announced plans to ease foreign travel restrictions to the U.S. beginning in November. The U.S. has largely restricted travel by non-U.S. citizens coming from Europe since the start of the pandemic, an issue that had become a point of contention in trans-Atlantic relations.

The new rules will allow foreigners in if they have proof of vaccination and a negative COVID-19 test, the White House said Monday.

Biden planned to limit his time at the United Nations due to coronavirus concerns. He was to meet with Australian Prime Minister Scott Morrison while in New York before shifting the rest of the week's diplomacy to virtual and Washington settings.

At a virtual COVID-19 summit Biden is hosting Wednesday, leaders will be urged to step up vaccine-sharing commitments, address oxygen shortages around the globe and deal with other critical pandemic-related issues.

The president is also scheduled to meet with British Prime Minister Boris Johnson on Tuesday at the White House, and invited the prime ministers of Australia, India and Japan — part of a Pacific alliance known as "the Quad" — to Washington on Friday. In addition to the gathering of Quad leaders, Biden will sit down for one-on-one meetings with Indian Prime Minister Narendra Modi and Japanese Prime Minister Yoshihide Suga.

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Madhani reported from Washington. Associated Press writers Jonathan Lemire in New York and Edith Lederer at the United Nations contributed to this report.