Iran and China are the most serious medium-to-long-term threats the Allies have to deal with. Both bear a family resemblance to pre-1914 Germany: repressive, authoritarian militaristic states with expansionist ambitions, contained by the dominant world powers. Both - like Imperial Germany - have had chances to reform themselves down more productive paths.
And like Imperial Germany they have not done so. I forget now who it was who said that in 1848 Germany reached a turning point and failed to turn: the revolution of that year could have given a decisive liberalising impetus, but the combination of unrealistic socialist revolutionaries, impractical liberal idealists and (above all) unimaginative and thuggish autocrats was fatal to Germany's chance of achieving the happy balance of a British-style constitution. Germany had at least two later chances - at the time of the struggle between Parliament and Bismarck in the 1860s, then again on Bismarck's dismissal in 1890 - but the old regime was too set in its ways to get off the long slide. The ultimate victim was European civilisation, which was mortally wounded in 1914 and finished off in 1945. (The Americans resurrected a version of it, partly for their own purposes, but it was a mere shadow of the original).
The Fairy Godmother of History gave the Chinese regime three chances. (Three, of course.) Tiananmen was the first: the Falun Gong cult the second: Hong Kong the third. (I take it as a given that China will continue trying to stifle HK's freedoms: if I'm wrong on that feel free to correct me.) In each case the regime was asked a question, but showed no sign of recognising that it had any option other than repression. The regime is not reformable any longer, if it ever was: it has been shown to be interested only in the first stage of reform - the kinds of reform that increase the efficiency of the system without giving up anything essential.
Iran has had its chances too. The death of Khomeini, the elections of 2000 and the regime change in Iraq all gave the regime a possibility for internal reform and - hand-in-hand with that - international co-operation and even amity. The Fairy Godmother was not given house room, however, and she's unlikely to return.
The great virtue of the West is that we usually get her message, if not at the first time of asking: authoritarian, nationalistic thug-states don't, and so procure their own ruin. Which wouldn't be a problem if they didn't take so much else - of beauty and value - with them into the night.