According to numbers from the U.S. Census Bureau, 80.7 percent of the U.S. population lived in urban areas as of the 2010 Census, a boost from the 79 percent counted in 2000. That brings the country's total urban population to 249,253,271, a number attained via a growth rate of 12.1 percent between 2000 and 2010, outpacing the nation as a whole, which grew at 9.7 percent.
No its not, because it has been common for decades. Case in point, WWII PT boats, Osa class missile boats, Pegasus class hydrofoils....
They have no legs and zero chance of surviving even a light anti-ship missile. There is a reason they are stationed in the Caspian Sea where range doesnt matter and they are not likely to face any state level actors.
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A city of 20,000 is an urban area though.