The strength of democracy?
I met people who claimed that the US is the No.1 military power because it is a liberal democracy. At the time, I gave them some slacks, because it was at least a slightly sounder argument than those who claimed "because it is a Christian country" which I also encountered in the past. Nevertheless, it doesn't mean that I don't find those arguments annoying, and I'm going to put some thoughts about it here.
America's military dominance was born of geography rather than political system. Being separated from two oceans, the country was able to sit out most of the WW1 and to keep itself safe from direct invasion in the second war, both of which devastated the Eurasia continent. With the other players in shambles, America simply filled the vacancy, controlling the post-war financial order with its intact economy, which was also the few post-war economies that could fund a big military force. It was how the USA gradually became the superpower we know today, and it was not due to the mode of governance.
The over-stress on "liberal" also obscure the fact that, contrary to modern perception, the US military was not always a technology-oriented force. Instead, it fought both world wars, Korea, and Vietnam War with the draft system and the strength of number it provides - that's right, the very "unliberal" conscription system. Throughout those conflicts, the US fielded a reasonably well-equipped force, but it was not overly superior to the other world powers in technology. Our impression today came from the contrast between the US and the enemies it actually fought in the Cold War, which were almost universally poor and ill-equipped. That, along with the transformation to all-volunteer system after Vietnam, gave birth to the modern perception of an elite, highly technological military force.
We also have to consider that the prevalence of stable democracies (I'm not even telling about liberal democracy) is itself a very modern thing. Before it became the largest democracy in the European continent, France experienced a series of convulsive and often violent periods of political transformation from late 19th century to around 1960s, during which it suffered three military defeats from authoritarian Germany; the first German democracy lasted for only a bit more than a decade, and for most of the second half of the 20th century, only half of Germany was a democracy; China's experiment with democracy was even briefer, and that period was marked with civil stratifies and upheavals. After that, it never ended up one.
So no, being a liberal democracy doesn't make your country a military superpower.