Finland becomes 31st member of Nato in Brussels ceremony

Formal accession nearly doubles Nato border with Russia as Moscow warns it will boost its defences if necessary

Finland has become the 31st member of Nato after its foreign minister, Pekka Haavisto, signed an accession document and handed it to the US secretary of state, Antony Blinken, at a ceremony in Brussels.

The handover marks the formal accession of Russia's western neighbour to the world's largest military alliance, completing an accelerated application process launched last May, when Finland and neighbouring Sweden abandoned decades of military nonalignment to seek security as Nato members after Russia's invasion of Ukraine.