I'd argue a lot has changed.
The U.S. has always militarily dominated everything that could hurt it. Soon after our independence, we were intervening in Latin America because in the 1800's, set off from the Old World by two huge oceans, Latin America is what could have hurt us. As the world became smaller, we built a bigger Navy, and by World War I we had the largest in the world. Ever since World War I we have maintained military supremacy in any domain that mattered (naval, air, nuclear, space, etc).
Arguably this is just a continuation of the trend onto the internet, now that the digital sphere matters.