They're undergoing a difficult time sure, but broke seems like a stretch.
Japan has struggled for 30 years, but during most of that time have they been broke? Most countries in the world would love to "struggle" like Japan.
What does broke mean?
China still has a currency earning export juggernaut and world class companies.
And, they build everything they need for war.
Russia with its energy and China with its manufacturing has sufficient assets to wage a World War 3 whether the U.S. wants it or not.
Wars aren't financed the same as peacetime economies.
Countries impress factories and manpower into service.
In some ways, if your country is sufficiently self sufficient, it's much cheaper than running a peacetime economy.
Of course, if you lose, then you're wrecked.