Finland is formally joining NATO on Tuesday in a move that doubles the military alliance’s border with Russia. Finland and Russia share an 800-mile border. Finland is joining NATO a week after Turkey’s parliament voted to ratify the Nordic country’s membership. Turkey and Hungary have yet to approve Sweden as a member of NATO, with Turkish President Recep Tayyip Erdoğan accusing Stockholm of harboring Kurdish dissidents he considers terrorists. Finland and Sweden had applied to join NATO in May 2022, just months after Russia’s invasion of Ukraine. For more on NATO’s expansion, we host a discussion between Reiner Braun, former executive director of the International Peace Bureau and longtime German peace activist, and Atte Erik Harjanne, a member of the Finnish Parliament for the Green League.