Finland set to join NATO amid Russian border warning.

Finland will become the 31st member of NATO on Tuesday, prompting a warning from Russia that it would bolster its defences in response. NATO Secretary General Jens Stoltenberg hopes Sweden, who applied for membership at the same time as Finland, will also be able to join NATO in the coming months. Finnish President Sauli Niinistö and Defence Minister Antti Kaikkonen will attend the ceremony along with Foreign Minister Pekka Haavisto. Russian Deputy Foreign Minister Alexander Grushko said Moscow would respond to Finland becoming a NATO member by bolstering its defences.