Finland formally confirms Nato membership bid
MAY 15: Finland's president has confirmed his country will formally apply for Nato membership - a move Vladimir Putin has described as a mistake
Sweden is also moving closer to joining the military alliance, as foreign ministers from the bloc continue talks in Berlin
On the ground, Ukrainian forces have pushed Russian troops "far out" from the north-eastern city of Kharkiv, the city's mayor has said
And Russia's offensive in Donbas, in the east, has lost momentum, according to UK military assessment
That UK report also says Russia may have lost a third of the ground combat forces it committed at the start of the invasion
Meanwhile, Ukraine has won the 66th Eurovision song contest - in a symbolic show of public support following the country's invasion
So what is Nato?
The Nato security alliance was founded in 1949, when a world war had given way to the Cold War.
The bloc aimed to counter Soviet expansion in Europe, and crucially, its founder members - the UK and US among them - agreed to come to each other's aid should one of them come under attack.
Nato expanded following the collapse of the Soviet Union, when Eastern European countries who were once members of the rival Warsaw Pact decided to join.
In recent years, there were questions over Nato's future. Former US President Donald Trump was a critic while French President Emmanuel Macron called the alliance "brain dead".
But with Russia's invasion of Ukraine Nato has been given a new importance.