Democratic presidential candidate Joe Biden has promised to end “forever wars” and reassert American leadership to combat authoritarianism and global instability he says are proliferating under President Donald Trump.

Mr Biden outlined his foreign policy vision in a speech in New York, indicting Mr Trump’s “America first” approach as belligerent, short-sighted, incompetent and ultimately threatening to US interests and democracy across the world.

“The world’s democracies look to America to stand for the values that unite us. … Donald Trump seems to be on the other team,” Mr Biden said, hammering the president for “embracing dictators who appeal to his vanity” and emboldening a worldwide rise of nationalism, xenophobia and isolationism.

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Democratic presidential candidate and former vice president Joe Biden speaks at Morris Brown AME Church (Meg Kinnard/AP)

The former vice president sought in his 43-minute speech to promise not just a return to the traditional US role in the post-Second World War international order, but to use that power and influence to take on 21st century problems.

Mr Biden emphasised the urgency for US-led global alliances to combat the climate crisis, forge new trade agreements to create a more even international economy and to recommit to nuclear proliferation.

If the US does not lead those efforts, Mr Biden said, “rest assured, some nation will step into the vacuum — or no one will, and chaos will prevail”.

The speech reflects Mr Biden’s belief that his decades of foreign policy experience, 36 years in the Senate and two terms as second-in-command to President Barack Obama, are an asset both in the crowded Democratic primary and against Trump.

But that long record also subjects the 76-year-old to substantial criticisms from the left and the right, particularly from progressives who cast Mr Biden as a willing cog in a more hawkish, bipartisan establishment that has guided world affairs for generations.

Nodding to those forces, Mr Biden promised to “end the forever wars in Afghanistan and the Middle East” and end US involvement in the Yemen civil war.

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Bernie Sanders (Steve Marcus/AP)

He did not mention his support for the 2003 invasion of Iraq under President George W. Bush, a vote that hampered Mr Biden’s brief 2007 presidential campaign and continues to draw criticism from rivals, including Vermont senator.

Bernie Sanders and Washington governor Jay Inslee, who both voted against the action as House members.

Republicans, meanwhile, have gleefully noted that Mr Biden opposed the 1991 US military actions to drive Iraq out of Kuwait and that he was an outlier in the Obama administration in warning his boss against the raid that ultimately killed Osama bin Laden, the mastermind behind the terrorist attacks of September 11 2001.

Mr Biden further highlighted his political tightrope with assurances that military force will always be an option even as he said it must be a “last resort” with a “defined” and “achievable mission”.

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North Korean leader Kim Jong Un, right, and US President Donald Trump cross the border line at the border village of Panmunjom (Korean Central News/AP)

Additionally, he pledged to “elevate diplomacy as the principle tool of our foreign policy”.

He noted the exodus of career State Department diplomats during the Trump administration and said he’d invest in rebuilding that expertise.

His promise to stop “endless wars” also came with qualification; he called for removing most combat troops from Afghanistan in favor of “narrowly focusing our mission” in the region.

The former vice president said in the first year of his presidency, he would convene a global summit of democracy, bringing together political and civic leaders, along with those from the private sector.

He singled out “tech companies and social media giants” as necessary partners.

“I believe they have a duty to make sure their algorithms and platforms are not used to sow division here at home,” he said, referring to US intelligence findings that Russian actors have used social media platforms like Facebook to influence American politics.

Mr Biden’s speech comes at a time of trade tensions with China; increasing tensions with Iran, with Tehran announcing that it is enriching uranium beyond the levels allowed by a 2015 nuclear deal that Mr Trump had abandoned; and after Mr Trump again met with North Korean dictator Kim Jong Un, with the Republican president saying he wants to restart negotiations for a nuclear agreement.

President Donald Trump (Evan Vucci/AP)

As president, Mr Biden said he would re-engage with Iran if they return to the limits of the 2015 deal. He also promised to immediately rejoin the Paris climate agreements and urge the world’s leading economies, principally China, to commit to aggressively curtail carbon emissions.

He noted Beijing is investing heavily in cleaner energy technologies but still financing traditional fossil fuel projects with trillions of dollars in infrastructure development across Asia.

Mr Biden’s commitment to “end the forever wars” stopped short of pledges by more liberal rivals like Mr Sanders and Massachusetts Senator Elizabeth Warren, who link military conflict to a world economy dominated by multinational corporations, including those that have benefited from the trillions of dollars the US has spent on foreign wars in recent decades.

Though he did not nod to that military-industrial complex, Mr Biden argued that economic conditions play a fundamental role in global stability.

He criticised Mr Trump’s reliance on tariffs but tacitly agreed with the president’s notions that some economic rivals have taken advantage of the US, specifically China.

Mr Biden said he would push for trade agreements that do not hamper the international exchange of goods but don’t disadvantage American consumers or business, while also holding China accountable for intellectual property abuses.

“There’s not going to be a back to business-as-usual on trade,” Mr Biden said.

“We need new rules. We need new processes.”