Different Cold War navies, different investments

Why was the United States behind in some Cold War naval areas?

It was not simply behind; different navies invested in different capabilities because their strategic circumstances and priorities differed.

The United States did not have to lead every naval technology simultaneously. American and Soviet investment overlapped in some fields and diverged completely in others. Geography, strategic priorities, institutional culture, treaty constraints, and expectations about a future war all shaped what each navy chose to fund. A capability that looks behind in isolation may simply have lost resources to an area judged more important. War provides the harsh test by revealing whether a navy predicted the operating environment well enough for its chosen compromises to work.