British Prime Minister Sir Keir Starmer says the NATO summit in Washington is a chance for its members to send a message to Russia following its "appalling" attacks on Ukraine.
The newly-appointed PM was speaking from Stanstead Airport, where he is due to fly to the US and meet with world leaders including Joe Biden and Volodymyr Zelenskyy.
His comments come after Russia launched one of its worst set of missile strikes on Ukraine in months, with at least 41 people killed and 166 injured.
The main children's hospital in Kyiv was among buildings hit in cities across the country yesterday.
Mr Starmer said: "My message is very, very clear that this NATO summit is an opportunity for allies to stand together, to strengthen their resolve, particularly in light of that appalling attack, against Russian aggression.
"I'm pleased to have the opportunity to affirm and reaffirm Labour's strong support, unshakeable support, for NATO.
"We are a founding member. It's now the 75th anniversary, but this is an opportunity to send that message in relation to Russian aggression wherever.
"But that attack last week was appalling. And so the message is even more important now than it was before."