Carrier experts in the navy have been gradually modifying the design and protection of the large carriers for decades, taking into account what new generations of large anti-ship missiles (“carrier killers”) could do. These design tweaks and damage control measures have been kept quiet, and often secret, to deny the anti-ship missile developers knowledge that they can use to improve their designs.
The U.S. Navy has also used old ships for target practice to see just how well these design changes perform in realistic conditions. For example, most of the 30 decommissioned Spruance class destroyers were used for this kind of target practice. Running a SINKEX (sinking exercise) enables the navy to test some theories on how vulnerable, or invulnerable, modern warships are. Carriers are rarely employed for this but a 1996 SINKEX was conducted using the retired 82,000 ton carrier USS America. This classified exercise was a test of the vulnerability of such large ships to modern anti-ship missiles. While the exercise details were secret, it did get out that carriers this size were very hard to sink.