DUBAI, UNITED ARAB EMIRATES — Iran unveiled an underground naval missile base at an undisclosed Gulf location on Saturday, state TV said, two days before the start of Donald Trump’s second term as president of the United States. It was unveiled at a time when tension with Washington is widely expected to rise. Iranian leaders are concerned that Trump might empower Israeli Prime Minister Benjamin Netanyahu to strike Iran’s nuclear sites, while tightening U.S. sanctions on its oil industry through his “maximum pressure” policy. State television showed Revolutionary Guards chief General Hossein Salami visiting the secret base during war games.