Finland has become the 31st member of the Nato security alliance, doubling the length of member states’ borders with Russia.
The Finnish foreign minister handed the accession document to the US secretary of state who declared Finland a member.
Then in bright sunshine in front of Nato’s gleaming new headquarters, Finland’s white-and-blue flag joined a circle of 30 other flags.
Finland’s accession is a setback for Russia’s Vladimir Putin.
He had repeatedly complained of Nato’s expansion before his full-scale invasion of Ukraine.
US Secretary of State Antony Blinken said by attacking his neighbour, the Russian leader had triggered exactly what he had sought to prevent.