Ukrainian President Volodymyr Zelensky has arrived in the UK for crunch talks with Rishi Sunak.
Mr Zelensky is meeting the Prime Minister at his official country retreat, Chequers, in Buckinghamshire.
Two RAF Chinook helicopters touched down on the lawn at the 16th Century mansion just after 9.15am, amid tight security
No10 said the PM would confirm the latest supply of vital military gear – including drones – to Kyiv as it prepares for its long-awaited counter offensive against Russian invaders.
Downing Street said: “Today the Prime Minister will confirm the further UK provision of hundreds of air defence missiles and further unmanned aerial systems including hundreds of new long-range attack drones with a range of over 200km.
“These will all be delivered over the coming months as Ukraine prepares to intensify its resistance to the ongoing Russian invasion.”
The PM said: “This is a crucial moment in Ukraine’s resistance to a terrible war of aggression they did not choose or provoke.
“They need the sustained support of the international community to defend against the barrage of unrelenting and indiscriminate attacks that have been their daily reality for over a year.
“We must not let them down.
“The frontlines of Putin’s war of aggression may be in Ukraine but the fault lines stretch all over the world. It is in all our interest to ensure Ukraine succeeds and Putin’s barbarism is not rewarded.
“That is why the UK is sustaining our support to Ukraine – from tanks to training, ammunition to armoured vehicles – and this message of solidarity will ring loud in all my meetings with fellow world leaders in the days ahead.
Mr Zelensky will be the first foreign leader Mr Sunak has hosted at his official grace-and-favour bolthole, 40 miles northwest of London.
Mr Zelensky tweeted: “The UK is a leader when it comes to expanding our capabilities on the ground and in the air.