No, it really doesn't. The army defends the nation and currency is an emergent property of the nation, but the army isn't out there with guns making sure people accept dollars. If you switched to Bitcoin and killed the US dollar, the army would still be needed to protect the country, to protect America's business interests abroad, its political interests abroad and its people. That would be true even if the currency was old shoelaces. The US army long predates the fiat dollar by about 200 years and there is absolutely, indisputably, no path to reducing cost or energy expenditure on the army when switching to a different currency.

Countries that use other countries currencies (in the way El Salvador uses the US Dollar) still have armies and some countries that use their own fiat dollars (Japan, Iceland) have no armies.

These two are uncorrelated.

Unless there's some straight line between, say, switching to Bitcoin and Xi Jinping realizing Taiwan was always its own country and grabbing some Baijiu with Tsai Ing-wen. I'm very excited to find out how Bitcoin solves the Hong Kong situation too! And I suppose it'll take care of business in the Sudan? Finally that trip to Yemen is back on the table. C'mon now...