The Prime Minister is set to hold an urgent press conference in Downing Street at 5pm.
The conference comes after he announced the government’s plan to boost defence spending, reports Sky News.
Speaking in the House of Commons at lunchtime, Starmer said that the UK defence spending will rise to 2.5%.
This will mean spending £13.4bn more on defence each year, the biggest increase in a defence budget since the Cold War.
Starmer is expected to issue a statement to the British public before taking questions.
Mr Starmer told the Commons: “We must find courage in our history, courage in who we are as a nation, because courage is what our own era now demands of us.
“So starting today, I can announce this Government will begin the biggest sustained increase in defence spending since the end of the Cold War.
“One of the great lessons of our history is that instability in Europe will always wash up on our shores, and that tyrants like Putin only respond to strength.
“Russia is a menace in our waters, in our airspace, on our streets, they have launched cyber attacks on our NHS, even seven years ago, a chemical weapons attack on the streets of Salisbury. We must stand by Ukraine.”
He is expected to discuss the budget increase at 5pm.
Related: Keir Starmer blasts ‘dangerous’ Nigel Farage for ‘fawning over Putin’