Liz Truss was due to land in New York today promising to keep pumping vital military kit into Ukraine.
The Prime Minister, on her first foreign trip since entering No10, vowed to hand Kyiv equipment worth billions of pounds, with at least as much support in 2023 as the UK has sent this year.
It comes as Ukrainians retake thousands of square miles of territory seized by Russia following its February 24 invasion.
Before her plane took off from the UK, Ms Truss said: “Ukraine’s victories in recent weeks have been inspirational.
“Time and time again these brave people have defied the doubters and showed what they can do when given the military, economic and political support they need.
“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 pledge will reassure hero President Volodymyr Zelensky that, like her predecessor Boris Johnson, Ms Truss will continue to back Ukraine’s resistance.
Battlefield gear sent from Britain is likely to include more Multiple Launch Rocket Systems, which experts say have helped Kyiv push back Russian forces.
Ms Truss’s address to the United Nations General Assembly in New York in the early hours of Thursday morning is set to be dominated by the war in Ukraine.
Downing Street said she would use her speech to “to underscore the UK’s long-term commitment to Ukraine, with no let up in our military, humanitarian and political support to the country”.
No10 added: “The UK is already the second largest military donor to Ukraine, committing £2.3billion in 2022.
“We have trained 27,000 members of the Ukrainian armed forces since 2015 and in the last year we have provided hundreds of rockets, five air defence systems, 120 armoured vehicles and over 200,000 pieces of non-lethal military equipment.”
Former Foreign Secretary Ms Truss will also use her trip to the States to press other countries to cut their reliance on Russian gas.
Downing Street accused Kremlin tyrant Vladimir Putin of trying to blackmail European nations but strangling supplies.
“As Putin struggles to maintain his hold in eastern Ukraine, he is using Russia’s grip on European energy supplies to economically blackmail the people of Europe,” said No10.
The claim comes after Moscow shut the Nord Stream 1 pipeline which pumps Russian gas to Germany.
Restricting energy supplies has unleashed turmoil on world markets, triggering spikes in prices, fuelling the cost-of-living crisis hammering British families.
The PM is expected to use one-to-one meetings with world leaders on the margins of the General Assembly to try and speed-up efforts “to stop Russia from profiting off its energy exports while ending energy dependence on authoritarian regimes”, No10 said.
Ms Truss added: “By turning off the taps of Nord Stream gas pipeline, Putin has consigned millions of people in Europe to a colder and more difficult winter.
“Too many lives – in Ukraine, in Europe and around the world – are being manipulated by a dependence on Russian energy. We need to work together to end this once and for all.”
The PM’s trip to the US has been shortened because of the Queen’s death.
Ms Truss flew from Stansted Airport in Essex yesterday evening after joining 2,000 mourners at the monarch’s funeral at Westminster Abbey.
She is due to meet US President Joe Biden in the Big Apple tomorrow, but is not expected to visit the White House.
Shadow Foreign Secretary David Lammy said: “Twelve years of Conservative governments making diplomatic gaffes, announcing plans to break international law, failing to live up to promises on climate action and cutting international aid have damaged relations with the US and left Britain isolated on the global stage.
“After being snubbed by the Biden administration within her first weeks in office, Liz Truss urgently needs to wake up to the damage her reckless approach to foreign policy is doing to the UK’s national interest.
“The Prime Minister must use the UN General Assembly to bring the UK back in from the cold and begin rebuilding our country’s diplomatic influence.
“In government, Labour would scrap the Conservatives’ lawless Protocol Bill and get back round the table with EU, restore the UK’s 0.7% aid target and restore the UK’s reputation as a trusted and reliable partner on the global stage.”
