The crises in Europe and the Middle East are very different but they are beginning to cross-infect each other, creating a general mood of uncertainty and fear. In the Middle East, the Arab Spring was at first seen as wholly positive, as dictatorships and police states tumbled or came under democratic assault from Tunis to Bahrain. A bright dawn was breaking across the region.

A year later, Syria, Egypt, Yemen, Bahrain and Libya are still beset by power struggles, largely electoral in Egypt but increasingly militarised in Syria. Their outcome is unclear. What is evident is that these countries are in for an extended period when governments and states will be weak, disunited and vulnerable to outside interference.

Such foreign intervention, going by what happened in Afghanistan and Iraq, is much the same as old-style imperialist takeovers. The interventionists consult their own interests first and last, largely ignoring the wishes of Iraqis or Afghans. Why, for instance, is the increasingly dictatorial Nouri al-Maliki prime minister of Iraq? Mainly, as one Iraqi politician put it to me, because "the Great Satan [the US] and the Axis of Evil [Iran] decided that he was the Iraqi leader they could both live with".

"Humanitarian" military intervention as advocated by Tony Blair – or, post 9/11, by George W Bush – turned out to be no such thing. The neo-imperialists invariably gave priority to what they deemed to be their own national interests. In practice, the Iraq and Afghan wars became exercises in damage limitation, in which governments in Washington, London and elsewhere sought to retreat without admitting to disastrous errors that would damage their political prospects at home. Thus, President Bush's policy in Iraq in 2004 was largely determined by his need to pretend to American voters in the presidential election that the war was going well when it was going disastrously badly. Likewise, there is something breathtaking about British ministers and generals speaking of the brotherly co-operation between Afghan and British forces after the latest killing of British soldiers by their Afghan colleagues.

In the past decade, the Muslim world had its grim reminders of the national egotism of great powers, notably that of the US. In Europe, people in states belonging to the European Union have had a different, less blood-soaked but no less compelling, demonstration of how little we have moved on from the Europe of contending nationalities. In the years before the financial crash of 2008, this was the dangerous but outmoded world that the EU was meant to be bringing to an end. Small nations such as Ireland, Portugal and Greece had once rushed into the warm embrace of the EU on the grounds that European solidarity would protect them in a crisis. Nationalism in England and France was seen as the province of the mindless right. For Ireland and Portugal, membership was particularly attractive as it reduced their dependence on their stronger neighbours (and past imperial overlords) Britain and Spain.

What Greeks, Iraqis and Afghans have all learned is that the price of foreign powers determining their future is very high. It always amazed me in Baghdad and Kabul that the Americans and British imagined that the Iraqis and Afghans did not notice or care that the US and its allies, and not local puppets, were mismanaging their affairs. Likewise, in Athens over the past six months, I found it astonishing that Germany and its allies could not see that imposing austerity on the Greeks without popular consent would be a political death warrant for the Greek political parties supporting the measures.

Of course, it was an illusion for the Greeks to imagine that, after entering the euro, they merited the same AAA credit rating as Germany. But then, in the heady days before 2008, with access to limitless amounts of cheap credit, every individual, institution and nation from Los Angeles home owners to Irish bankers to the Greek government behaved with a similar lack of realism.

There were highly informed people in Athens only a few months ago who believed that the only chance of genuine reform in Greece was through pressure from the Troika (EU, IMF and ECB). I remember one investigative journalist brandishing a list of names of taxpayers, with one column showing their declared incomes and a second column their real, and much higher, incomes. "The banks only gave up the information because of pressure from the Troika," he said.

This is not now going to happen. When the then Greek prime minister, George Papandreou, suggested that there should be a referendum on the deal with the EU he was treated as a pariah by other EU leaders. German ministers seemed to think it smart politics to abuse Greece because that was what German taxpayers wanted to hear. All this inevitably sabotaged the efforts of any Greek politician advocating acceptance of the EU's terms.

The European and Middle East crises are in their different ways exposing as claptrap optimistic talk of European solidarity, globalisation being beneficial to all, and "humanitarian" intervention. As mutinies against the powers-that-be spread across Europe, the natural conduit for political activism is strongly nationalist parties on the right and the left. Many voters may feel that angry nationalists may be able to cut a better deal with Brussels than their over-complaisant predecessors. The age of competing nationalities, which never really ended, is back with a vengeance.