Rishi Sunak has promised more support for Ukraine as Nato's Secretary General prepares to visit Downing Street.
Jens Stoltenberg will be the first international leader to visit Downing Street since Mr Sunak became Prime Minister last month.
The UK is to send a further 12,000 extreme cold weather sleeping kits and 150 tents to Ukrainian troops as they face the onset of freezing winter conditions.
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Britain is also due to deliver more than 25,000 sets of extreme cold weather clothing by mid-December.
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Mr Stoltenberg will also visit Ukrainian soldiers receiving training from UK counterparts at Lydd Army training camp in Kent on Operation Interflex. Recruits on the operation have received more than 7,000 sets of normal cold weather kit.
Mr Sunak says peace in the UK cannot be taken for granted while Vladimir Putin wages war in Ukraine.
The Government is examining how to update its integrated review of defence and foreign policy to ever-changing global threats.
Ahead of Mr Stoltenberg's visit, Mr Sunak said: "Nato is the cornerstone of our security and the security of our allies.
"As the war in Ukraine continues to rage, we must not take peace at home for granted.
"I am determined the UK will be the bedrock of Nato for generations to come.
"But, in order to face the challenging future, we must evolve as an alliance to meet, and remain ahead of, the threat from our adversaries.
Watch: Starmer 'so impressed' with UK military's training of Ukrainian troops.
"We must also continue backing the Ukrainian people in their resistance to Putin's brutality."
Mr Sunak added: "I'm pleased that UK-donated kit will be keeping the Ukrainian Armed Forces warm and safe as they face a perilous winter fighting for their country."
Defence Secretary Ben Wallace said: "With winter fast approaching, this equipment will ensure that the Armed Forces of Ukraine are able to operate effectively through the next few months.
"Alongside our training programme and the provision of lethal aid, it demonstrates our commitment to making sure that the basic Ukrainian soldier is well trained, well equipped and given the best possible chance to fight and determine their own future."