US President Joe Biden has mapped out a new era of vigorous competition without a new Cold War despite China's ascendance during his first United Nations address, promising military restraint and a robust fight against climate change.
The United States will help resolve crises from Iran to the Korean Peninsula to Ethiopia, Biden told the annual UN General Assembly gathering.
The world faces a "decisive decade," Biden said, one in which leaders must work together to combat a raging coronavirus pandemic, global climate change and cyber threats.
He said the United States will double its financial commitment on climate aid and spend $US10 billion ($A14 billion) to fight hunger.
Biden did not ever say the words "China" or "Beijing" but sprinkled implicit references to the increasingly powerful authoritarian competitor throughout his speech as the two countries butt heads in the Asia-Pacific and on trade and human rights issues.
He said the United States will compete vigorously, both economically and to push democratic systems and rule of law.
"We'll stand up for our allies and our friends and oppose attempts by stronger countries to dominate weaker ones, whether through changes to territory by force, economic coercion, technical exploitation or disinformation. But we're not seeking - I'll say it again - we are not seeking a new Cold War or a world divided into rigid blocs," Biden said.
Biden came to the United Nations facing criticism at home and abroad for a chaotic US withdrawal from Afghanistan that left some US citizens and Afghan allies still in that country and struggling to get out.
His vow for allied unity is being tested by a three-way agreement among the United States, Australia and the United Kingdom that undermined a French submarine deal and left France feeling stabbed in the back.
"We've ended 20 years of conflict in Afghanistan and as we close this era of relentless war, we're opening a new era of relentless diplomacy," Biden said.
Biden vowed to defend vital US interests but said that "the mission must be clear and achievable," and the US military "must not be used as the answer to every problem we see around the world".
Biden added that he remains committed to peacefully resolving a dispute with Iran over its nuclear program.
He vowed to defend US ally Israel but said a two-state solution with the Palestinians is still needed but a distant goal.
He said the United States wants "sustained diplomacy" to resolve the crisis surrounding North Korea's nuclear and ballistic missile programs.
North Korea has rejected US overtures to engage in talks.
Discussing oppression of racial, ethnic and religious minorities, Biden singled out China's Xinjiang region where rights groups estimate that one million Uighurs and other ethnic minorities have been interned in camps.
In response to Biden's reference to Xinjiang, China's mission to the United Nations, told Reuters: "It's completely groundless. We totally reject. The US should pay more attention to its own human rights problems."
UN Secretary-General Antonio Guterres, who begins a second five-year term at the helm of the world body on January 1, warned earlier of the dangers of the growing gap between China and the United States, the world's largest economies.
"I fear our world is creeping towards two different sets of economic, trade, financial and technology rules, two divergent approaches in the development of artificial intelligence - and ultimately two different military and geopolitical strategies," Guterres said.
"This is a recipe for trouble. It would be far less predictable than the Cold War," Guterres said.
Australian Associated Press