The UK will match the support it has provided to Ukraine this year in 2023, Liz Truss has pledged.
Ukraine's army has reclaimed swathes of occupied territory in the east of the country in recent weeks, forcing Russian troops to retreat.
In her first foreign trip as prime minister, Ms Truss is expected to point to this success as evidence of what the Ukrainian people can do with the backing of fellow democracies.
Ms Truss is visiting New York for the annual United Nations General Assembly (Unga), where she will hold meetings with Joe Biden and Emmanuel Macron as political action resumes after the period of national mourning for the Queen.
She is expected to use the trip to underscore the UK's long-term commitment to Ukraine, while also stressing the need to remove energy dependence on Russia.
When asked what she was hoping to get from her meeting with the US president, she told reporters: "The number one issue is global security - making sure we are able to collectively deal with Russian aggression and ensuring that Ukraine prevails and Putin doesn't have success in Ukraine.
"(It's a) huge priority for European security as well as ensuring that we are working together with other members of the G7 to make sure we are not strategically dependent on authoritarian regimes. That's the priority."
The UK is already the second largest military donor to Ukraine, committing £2.3bn in 2022 while providing hundreds of rockets, air defence systems and non-lethal military equipment.
Ahead of the trip, Ms Truss confirmed the UK will meet or exceed the amount of military aid spent on the war-torn nation in 2022 next year.
She said: "My message to the people of Ukraine is this: the UK will continue to be right behind you every step of the way. Your security is our security."
The visit comes against the backdrop of Brexit tensions and questions over whether Ms Truss regards the French leader a "friend or foe".
While she hopes the focus will be largely on energy security and combating Russia's war in Ukraine, clashes over the Northern Ireland Protocol are bound to feature.
Truss 'wants constructive relationship with Macron'
Mr Biden, the US President with proud Irish heritage, has raised concerns about Brexit's threat to the peace process and has downplayed the chances of striking a free-trade deal.
His French counterpart, Mr Macron, has long been a critic of Brexit and has been firm in pressing the UK to keep to commitments on Northern Ireland and fishing rights.
Ms Truss sparked a diplomatic row during the Tory leadership contest when she declined to give a clear answer when asked if the French president was a "friend or foe".
Instead, the then-foreign secretary said that the "jury's out".
When questioned on Monday night, ahead of arriving in the US, about the UK's relationship with France, in particular over Channel migrants, Mr Truss said she wanted to have "a constructive relationship with France".
"Of course that means working together on the issue of migration. There are a number of other issues we need to work together on whether it's energy security, whether it's other issues relating to our relationship with the EU - but most importantly, it's ensuring that Putin does not succeed in Ukraine.
"That's what I'll be discussing with President Macron."
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Ms Truss will meet Mr Macron and Ursula von der Leyen, the president of the European Commission, on Tuesday, before seeing Mr Biden on Wednesday.
Meetings with Turkey's Recep Tayyip Erdogan, Spain's Pedro Sanchez and Israel's Yair Lapid are also scheduled.
Ms Truss will also deliver a speech to the UN General Assembly, where she will say the UK under her leadership will be "an active defender of our democratic values" and will work to counter authoritarianism with allies.
The trip kicks off a frantic few days of political action in Ms Truss' fledgling premiership, with details on how businesses will be helped through the energy crisis and a major announcement on the NHS billed.
Ms Truss, who is being joined by Foreign Secretary James Cleverly in the US, will then return ahead of Chancellor Kwasi Kwarteng's mini-budget on Friday.