The protagonist is an older officer, possibly one who started his career in an ocean-going navy; the rest of the crew is younger, and probably multi-national.
The setting is a command satellite for a cloud of laser/particle beam satellites deployed in orbit as a defence against nuclear war (and maybe also a means of retaliation). If I'm recalling correctly there are 3 (if I'm wrong there are more, not fewer) command satellites, each controlling a share of the lasers. The defense is international; command of the stations is split among the powers. (I think one is U.S. commanded, one is Chinese and the third is Russian/Soviet.) The crews themselves, however, are drawn from all over the world; I recall characters from Europe, India, etc. There is some friction between the commander and his crew, or perhaps a lack of respect from them.
The commander receives a message by some covert channel from one of the other commanders; they are going to jointly declare martial law over Earth and take power. He doesn't wish to do this, but is threatened with being shot down if he doesn't join the conspirators. He stalls for time and starts lowering the orbit of the station. When they notice, the other stations take this as evidence that he is going to work against them, and start attacking.
The attacks are carried out by the finger-of-god satellites; by lowering orbit he has reduced the number of enemy satellites that can be brought to bear. His crew finally start working together; enemy satellites that come into range are shot at, one of the young commanders thinks of using their shuttlecraft as active armour, and a young engineer organizes a damage-control party. (I'm reasonably sure she was European, and he was Indian.)
The damage control party tries to beat the odds by chasing salvos (that specific term was used), but ultimately the odds catch up to them. Fortunately their sacrifice was not in vain, because before the satellite can be completely crippled, Earth manages to take back control of the other command stations, ending the threat.