Complex sentence: Tensions were running high when on Friday, November 9, as the Leary and the Newport News were operating in the waters northeast of Cuba, one of the first Soviet vessels, the "Labinsk", approached the Navy blockade.
Split into simpler sentences: Tensions were running high when on Friday, November 9, the Leary and the Newport News were operating in the waters northeast of Cuba. Suddenly, one of the first Soviet vessels, the "Labinsk", approached the Navy blockade.