where he served on a destroyer. Something that I did a bunch of research on when taking a history class in college.
And they aren't sending a destroyer to launch a missile, they are sending (according to one source) 3 Aegis class cruisers. Which are somewhat different ships. Destroyers have the primary role of defending the fleet (which has been their role since WWII) from submarine and surface action. Still their primary role.
They are much more capable now than in WWII.
Here is a good definition for you...
n the US Navy, destroyers operate in support of carrier battle groups, surface action groups, amphibious groups and replenishment groups. The destroyers currently in use by the US Navy are the Arleigh Burke-class. Destroyers (with a DD hull classification symbol) primarily perform anti-submarine warfare duty while guided missile destroyers (DDGs) are multi-mission (anti-submarine, anti-aircraft, and anti-surface warfare) surface combatants. The relatively-recent addition of cruise missile launchers has greatly expanded the role of the destroyer in strike and land-attack warfare. As the expense of heavier surface combatants has generally removed them from the fleet, destroyer tonnage has grown (a modern Arleigh Burke-class destroyer has the same tonnage as a World War II light cruiser). Arleigh Burke is billed by her builders as ton-for-ton the most powerful warship in history.
from
http://en.wikipedia.org/wiki/DestroyerSo, yeah, they do have bigger missions than their old WWII counterparts... but the main role of support of carrier battle groups, especially in anti-submarine, anti-surface, and anti-air (though the carriers OWN air defense as embodied in the role of at least one air wing is likely superior to that of any surface ship). And, yeah, before you lose a carrier, the destroyer is the vessel you put in harms way. So in that sense, they are expendable. But not at a cost of $3B per ship!