An interesting story is undermined somewhat by wan acting until about the last third, when Cassavetes finally shows some emotion. Once they get aboard the Seaview the tension finally kicks in. The exchange between the Chief and Riley in the corridor was an uncommon pleasure, with the focus being on secondary characters and their dialogue ringing true.
Minor quibbles include the suspicion that Nelson and Crane would have been killed at the beginning, being that close to a "proton explosion." Also the characterization of the commie Chinese general or whatever he was at the beginning was SCTV laughable.
I suspect that some current Fox News talk show hosts would take exception to the Admiral's statement that " ... no one individual or country should have the majority of power ... " in the world.