Massachusetts Air National Guard member Jack Teixeira was sentenced on Tuesday to 15 years in prison for leaking online highly classified US military documents, including some related to Russia’s invasion of Ukraine. Teixeira, 22, was sentenced by US District Judge Indira Talwani in Boston after pleading guilty in March to perpetrating what federal prosecutors have called “one of the most significant and consequential violations” of US anti-espionage law ever committed. He apologized in court for his actions. “I’m sorry for all of the harm that I’ve brought and that I’ve caused,” Teixeira, dre…