Finland on Thursday said it would extend its border closure with Russia “until further notice,” after it was shut in response to a surge in migrant crossings. Finland, which joined the NATO military alliance following Russia’s invasion of Ukraine, says the surge in asylum seekers has been orchestrated by Russia, a charge that Moscow has denied. The two neighbors share a 1,340-kilometer (830-mile) border. The Nordic country closed the border in mid-December after nearly 1,000 migrants had arrived without a visa through its border crossings with Russia since August. Finland has since extended th…