conducting a full investigation into the security lapses there. david? >> matt gutman reporting tonight. matt, thank you. hundreds of former prisoners in oklahoma are marking their first taste of freedom tonight, days after the state's parole board commuted the sentences of 527 inmates. the largest mass commutation in u.s. history. it comes after criminal justice reforms changed some low-level felonies to misdemeanors. the move will also save taxpayers nearly $12 million. we turn tonight to an abc news exclusive. this evening, we take you onboard a nuclear-powered u.s. navy submarine, a guided missile submarine now on a classified mission tonight. we were there in the eastern mediterranean, where they're not the only ones in the sea. tonight, the tomahawks, the torpedos, the nuclear reactor and the warning about the russians right there, too. we approach the "uss florida" in the eastern me prepares for a highly classified mission. so, this is 18,000 tons we're looking at. >> 18,000 tons of american steel out there.