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Nato's General Secretary has welcomed Finland and Sweden's joint application to enter the Western alliance after Russia’s invasion of Ukraine and the devastation of the former Soviet country, describing the bid as “historic”.
The two countries handed over their application documents to Jens Stoltenberg early on Wednesday in Brussels.
"The applications you have made today are a historic step,” he said. “Allies will now consider the next steps on your path to Nato. This is a good day at a critical moment for our security.”
The bid could lead to the most significant expansion of Nato in decades, doubling the length of its border with Russia, and President Vladimir Putin has warned the bloc it may trigger a response from Moscow.
The applications face resistance from Nato member Turkey, which has threatened to block them over accusations that the Nordic neighbours act as safe havens for armed groups opposed to Ankara.
"The security interests of all allies have to be taken into account and we are determined to work through all issues and reach rapid conclusions," Mr Stoltenberg said. "All allies agree on the importance of Nato enlargement. We all agree that we must stand together."
Antony Blinken, the US Secretary of State, will meet Turkish officials on Wednesday in New York in a new effort to clarify Ankara’s position.
President Recep Tayyip Erdogan has said the two nations harbour security threats. “Neither country has an open, clear stance against terrorist organisations,” he said this week. “We cannot say ‘yes’ to those who impose sanctions on Turkey, on joining Nato, which is a security organisation.”
Ambassadors are expected to discuss the applications on Wednesday and could give approval on opening formal talks.
Several allies, most notably Britain, have offered security assurances to Finland and Sweden during the application period before they are covered by alliance's mutual defence pact.