Sir Keir Starmer would put British troops in Ukraine to help guarantee a peace deal.
The US and Russian Presidents are holding talks on the war - but excluding EU nations, including Ukraine.
Starmer's said lasting peace is essential to deterring future aggression by Vladimir Putin - and he doesn't take putting British servicemen and women in harm's way lightly, but he'll do what it takes to guarantee Ukrainian security.
UK correspondent Gavin Grey says there's fears about what Putin will take in a peace deal - and European leaders are set to express their concerns at the upcoming emergency summit in France.
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