Submarines!
By My latest at the Diplomat thinks through the implications of the deal to purchase 10 new Virginia class subs.
The USN has maintained a consistent nuclear attack submarine capability since the 1950s. Initially focused on anti-shipping missions, over time the SSN force has developed critical anti-submarine warfare (ASW), recon, land attack, and even Special Operations Forces (SOF) roles. More so than aircraft carriers or even manned aircraft, we can expect that the USN will continue to need modern subs to manage these missions over the lifespan of these boats. The fleet has proven so successful over the past decades that attack subs are likely to acquire more missions, not fewer.