HELSINKI (Reuters) -Security concerns raised by Turkey in its opposition to Finland’s and Sweden’s NATO membership applications are legitimate, NATO Secretary General Jens Stoltenberg said on Sunday during a visit to Finland. “These are legitimate concerns. This is about terrorism, it’s about weapons exports,” Stoltenberg told a joint news conference with Finnish President Sauli Niinisto while visiting him at his summer residence in Naantali, Finland. Sweden and Finland applied to join the Western defence alliance last month, in response to Russia’s invasion of Ukraine. But they have faced opp…