Finland is poised to join NATO on Tuesday, a historic realignment brought on by Russia’s invasion of Ukraine, but the head of the military alliance said it would not send more troops to the Nordic country unless it asked for help. Russia has already warned that it would bolster defenses along its border with NATO if the alliance deploys any additional troops or equipment to its new member. “There will be no NATO troops in Finland without the consent of Finland,” NATO Secretary-General Jens Stoltenberg told reporters at NATO headquarters in Brussels a few hours before the country joins. But he refused to rule out the possibility of holding more military exercises there and said that NATO would not allow Russia’s demands to dictate the organization’s decisions. “We are constantly assessing our posture, our presence. We have more exercises, we have more presence, also in the Nordic area,” he said. Later Tuesday, Finland is set to officially become the 31st member of NATO and take its place among the ranks of the world’s biggest security alliance. Alarmed by Russia’s invasion of Ukraine last year, Finland applied to join NATO in May, setting aside years of military non-alignment to seek protection under the organization’s security umbrella. Neighboring Sweden also applied, but its accession process may take a few months longer. Finland shares a 1,340 kilometer (832 mile) border with Russia, so its entry will more than double the size of NATO’s border with Russia. The move is a strategic and political blow to President Vladimir Putin, who has long complained about NATO’s expansion toward Russia. Russia’s Deputy Foreign Minister Alexander Grushko said Monday that Moscow would respond by bolstering its defenses if needed.