The world at the beginning of the 21st century bears an eerie — and disquieting — resemblance to Europe at the beginning of the last century.
That was also an era of globalisation. New technologies for transportation and communication were transforming the world. Europeans had lived so long in peace that war seemed irrational. And they were right, up to a point.
The first world war was the product of a mode of rational thinking that went badly off course. The peace of Europe was based on security assurances. Germany was the protector of Austria-Hungary, and Russia was the protector of Serbia.
The prospect of escalation was supposed to prevent war, and it did — until, finally, it didn't. The Russians, who should have been deterred — they had suffered a terrible defeat at the hands of Japan just a few years before — decided they had to come to the support of their fellow Slavs.
As countries honoured their commitments, a system that was designed to prevent war instead widened it.
We have also been living in an age of globalisation, especially since the end of the cold war, but it too is increasingly being challenged.
And just like the situation at the beginning of the last century, deterrence is not working. Much is made, for example, of the North Atlantic Treaty Organisation (NATO) invoking Article V — the famous "three musketeers" pledge that an attack on one member is to be considered as an attack on all — following the terrorist attacks of September 11.
But the United States is the most powerful member of NATO by far. Indeed, in 2001, it was widely considered to be a hegemon, a hyperpower. Other countries wanted to be in NATO because they felt an American guarantee would provide security.
And yet it was the US that was attacked.
This failure of deterrence has not received the attention it deserves. It is, after all, not unique. The North Vietnamese were not deterred by the American guarantee to South Vietnam. Similarly, Hezbollah was not deterred in Lebanon in the 1980s, and American forces were assaulted in Somalia. What has been going wrong?
The successful deterrence of the superpowers during the cold war led to the belief that if such powerful countries could be deterred, then lesser powers should fall into line when confronted with an overwhelmingly powerful adversary.
It is plausible, but it may be too rational. For all their ideological differences, the US and the Soviet Union observed red lines during the cold war. There were crises — Berlin, Cuba, to name a couple — but these did not touch on emotional issues or vital interests, so that compromise and retreat were possible.
Indeed, what we may have missed in the west is the importance of retreat in Soviet ideology. "Victory is impossible unless [the revolutionary parties] have learned both how to attack and how to retreat properly," Lenin wrote in Left-Wing Communism: An Infantile Disorder. When the Soviets retreated, the US took the credit. Deterrence worked. But what if retreat was part of the plan all along?
What if, in other words, the Soviet Union was the exception rather than the rule?
That question is more urgent because, in the post-cold war world, the US has expanded its security guarantees, even as its enemies show they are not impressed.
The Iraqi insurgents were not intimidated by President Bush's challenge to "bring 'em on". The Taliban have made an extraordinary comeback from oblivion and show no respect for American power. North Korea is demonstrating increasing belligerence.
And yet the US keeps emphasising security through alliances. "We believe that there are certain commitments, as we saw in a bipartisan basis to NATO, that need to be embedded in the DNA of American foreign policy," secretary of state Hillary Clinton affirmed in introducing the new National Security Strategy.
But that was the reason the US was in Vietnam. It had a bipartisan commitment to South Vietnam under the Southeast Asia Treaty Organisation, reaffirmed through the Tonkin Gulf Resolution, which passed Congress with only two dissenting votes. It didn't work, and found its commitments were not embedded in its DNA. Americans turned against the war, Secretary Clinton among them.
The great powers could not guarantee peace in Europe a century ago, and the US could not guarantee it in Asia a half-century ago.
Before the US makes further guarantees, it needs to understand the reasons for these failures, lest new promises lead to tragedy both for the US and those who would put their trust in it.