UNITED NATIONS — President Biden summoned the world’s nations to forcefully address the festering global issues of the COVID-19 pandemic, climate change and human rights abuses in his first address before the U.N. General Assembly on Tuesday. He decried military conflict and insisted the U.S. is not seeking “a new Cold War” with China.

The president said the halting of U.S. military operations in Afghanistan last month, ending America’s longest war, set the table for his administration to shift its attention to intensive diplomacy at a moment with no shortage of crises facing the globe.

“To deliver for our own people, we must also engage deeply with the rest of the world,” he said.

He added: “We’re opening a new era of relentless diplomacy, of using the power of our development aid to invest in new ways of lifting people up around the world.”

Biden offered a robust endorsement of the U.N.’s relevance and ambition at a difficult moment in history, and sought to reassure wary allies of U.S. cooperation after disagreements in recent months.

He also pledged to double U.S. financial aid to poorer countries to help them switch to cleaner energy and cope with the “merciless” effects of climate change. That would mean increasing assistance to about $11.4 billion a year. This after five months ago doubling the amount to $5.7 billion a year.

As part of the fight against climate change, rich nations for many years have promised to spend $100 billion a year in climate help, but a new study shows that they’re $20 billion a year short. Biden said his new commitment would help rich nations reach their goal.

The $100 billion goal is key because in climate negotiations there’s a dramatic rich-poor nation gap. Developing nations and others are reluctant to curb emissions further of heat-trapping gases without help from developed nations, which in the words of British Prime Minister Boris Johnson, are “the guys that created the problem.”

Biden is 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 Donald 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.

Biden wasn’t so concerned. Asked by a reporter as he arrived at the U.N. on Tuesday how he planned to repair relations with the French, Biden responded with two words: “They’re great.”

Before Biden’s arrival in New York, EU Council President Charles Michel on Monday 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.

In an interview before his meeting with Biden, U.N. Secretary General Antonio Guterres told the Associated Press that he was concerned about the “completely dysfunctional” U.S.-China relationship and the possibility it could lead to a new Cold War.

The secretary-general did not back off his concerns about the U.S.-China tensions as he addressed leaders at the opening of Tuesday’s gathering. “It will be impossible to address dramatic economic and development challenges while the world’s two largest economies are at odds with each other,” he said.

Biden sought to play down concerns about China tensions escalating into something more, saying: “We are not seeking a new Cold War or a world divided into rigid blocs.”

More broadly, he put a heavy emphasis on the need for world leaders to work together on the COVID-19 pandemic, to meet past obligations to address climate change, to head off emerging technology issues and to firm up trade rules.

“We will choose to build a better future. We, you and I, we have the will and capacity to make it better. Ladies and gentlemen, we cannot afford to waste any more time,” he said. “We can do this.”

Biden planned to limit his time at the United Nations due to coronavirus concerns. He met with Australian Prime Minister Scott Morrison in New York following his speech, but was set to shift the rest of the week’s diplomacy to virtual and Washington settings.

Morrison and Biden did not comment on the flap with the French when they appeared briefly before the media at the start of their meeting. Morrison, however, praised Biden for understanding the complexities of the situation in the Indo-Pacific.

“There’s no doubt you get it,” the prime minister told Biden.

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 was 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.

Biden defended his decision to end the U.S. war in Afghanistan, a chaotic withdrawal of American troops that frustrated some allies and hurt his standing at home. He called for the world to make the use of force “our tool of last resort, not our first” going forward.

“Today, many of our greatest concerns cannot be solved or even addressed by the force of arms,” he said. “Bombs and bullets cannot defend against Covid-19 or its future variants.”

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