The Navy has finally admitted its role in the discovery of HMS Titanic in 1985. It seems Ballard's original mission was to make detailed surveys of the lost submarines Thresher and Scorpion. Ballard finished ahead of time, and, since Titanic was thought to be between the two wrecks, he sort of took the long way home.

I'm not completely sure this is all of "the rest of the story," as I recall reading vague references to Ballard's mission being used to "send a message" to the Soviets about certain capabilities the Navy had developed. Nobody that I know of has been specific as to what these were.

Another "Western Union by Other Means" test that I've heard of is STS-2, space shuttle Columbia's second flight. According to things I've read, the widely-publicized radar test which revealed the presence of ancient riverbeds crisscrossing the Sahara was actually meant to demonstrate the US's ability to image hidden Soviet bunkers and missile silos. At least, that's what I've heard at any rate. YMMV!