The United States said it would offer aid to "friendly, innocent neutral vessels flying a nonbelligerent flag" if they came under attack.

Her only sightings during this patrol were two friendly Soviet vessels and a momentary contact with a small patrol craft.

"Is there a friendly vessel charted anywhere in the area?"

This helps disguise the total number and location of friendly vessels present.

It might be possible to transfer water from a friendly vessel, but first things first.

And what if Dansitt's sub should spot us before a friendly vessel might?

The last two are escort missions: guarding a friendly vessel to its destination.

"We should also be on guard for tensions from otherwise friendly vessels," T'ationoy suggested.

Anything else will give rise to absurd or dangerous situations, and the system must be weighted in favour of environmentally friendly vessels.

The object of the game is to destroy incoming enemy spacecraft, bombs, missiles, asteroids, etc. without destroying friendly vessels.