In July 1971, Henry Kissinger got into a small plane in Islamabad and briefly disappeared off the map. The official story for the next couple of days was that he was ill, but in fact President Nixon's right-hand man was on a secret journey to Beijing that would electrify the world. It was a period when the US was constantly redefining the possible. Just two years before it had put the first man on the moon. While the physical challenges of building diplomatic ties with Mao's China were not quite comparable, politically it felt like the equivalent of smashing through the stratosphere.
It says much about the dangerous tilt of the world that when we meet – 43 years later – we find ourselves talking about the possibility of war between the US and China. The subtle diplomatic architecture that Kissinger constructed in those historic visits looks increasingly under threat. In his new book, World Order, he cites a Harvard study that shows that in 10 out of 15 cases, when there's an established power and a rising power, war ensues. I ask him how likely he thinks conflict is, and what can be done to avoid it.
"Both President Obama and President Xi – President Xi particularly – have said they would like the relationship to demonstrate how tensions actually could be dispersed between a rising power and an existing power," he replies in his distinctive lugubrious gargle. "But having said that, they have not been able to give it a practical expression. And I think it is a huge problem."
Referring to the simmering tensions over the South China Sea Islands, he says, "Sooner or later one of them is going to lead to a confrontation. I don't want China and the US to be like Germany and Britain in 1914, but I don't think we can resist it primarily by military deployments along the Chinese border. So the question is: can we create a space between ourselves and China... with an American military presence being on the horizon but in which we can compete by some established rules?"
We meet on a clear blue September day in New York at the offices of Kissinger Associates, the international consulting firm that he runs with Brent Scowcroft, also a former US National Security Advisor. Though Kissinger is 91 and is recovering from a recent heart-valve operation, the overwhelming impression in his offices is of youth, as good-looking young men and women flit discreetly in and out of different doors. Kissinger once said of Mao: "He had the quality of being at the centre of wherever he stood". It was a trait he deeply admired, and he has cultivated it in himself. Despite the fact that he is the shortest person in his office and now uses a stick, the aura of power is unmistakable as he walks into reception and surveys me, blinking, a cross between Cardinal Richelieu and a European eagle-owl.
Kissinger's enduring magnetism for world statesmen almost certainly dates from his success in gaining the US President an invitation to meet Mao. That meeting marked his rise from senior politician to international phenomenon, one of the most glitteringly divisive figures of his time. The statesman "must act at the outer edge of what is possible," he declares at one point in his book, "bridging the gap between his society's experiences and its aspirations."
Throughout his life, this has been the conceptual territory in which Kissinger has thrived. Whether in approaching China, achieving détente with Russia, or reversing hostilities between Egypt and Israel in 1973, his ability to balance complex personalities and weave together conflicting cultures has been conducted with the intuitive flair described in his native German as Fingerspitzengefühl.
His continuing potency on the political front-line is demonstrated not least by Hillary Clinton's somewhat extraordinary – but rightly enthusiastic – review of his book shortly before we meet. He in return has indicated, despite his Republicanism, that he believes she would make a good president. I ask what qualities she demonstrated as Secretary of State that makes him believe this?
He smiles. "She ran the state department as an institution better than I've ever seen it – including [under] myself. I'm not as precise as she is. She came into office at a complicated moment as a member of an administration that wanted to make a drastic change. Her own views were not as drastic as those of the incumbent President on these matters. She handled her relationships with enormous skill and I have never heard her say one critical world about the President. I will support the Republican candidate, because I think we need a change, and I've said that publicly, but I am very positive about her."
The elasticity of his statement is classic Kissinger. As well as containing a none too subtle sideswipe at Obama, it is both a declaration of support and not a declaration of support for Clinton that can be adapted according to whichever way the political wind is blowing. That chameleon aspect of his personality has often been remarked upon – who exactly Henry Kissinger is has preoccupied many people who have had close dealings with him.
At the most surprising end of the spectrum, he has been an unlikely sex symbol. He has been photographed with women including Elizabeth Taylor, Raquel Welch, Liza Minnelli, and much later Princess Diana – in recent years Carla Bruni has been among the glamorous women with whom he has been snapped. In 1972, the year Nixon himself went to China, Kissinger was even mocked up as a reclining nude in an edition of the Harvard Lampoon that went on to sell over 1.1m copies. When the then president of the USSR, Leonid Brezhnev, was shown a copy, he had it pinned up in his office.
Yet it has been Kissinger's more subtle incarnations that have most taunted both his allies and his detractors. His ability to work at the "outer edge of the possible" is connected to his tendency to see the world as a series of shifting realities. This has been argued as both the essence of his genius and a character flaw. The late international-relations expert Hans Morgenthau, a former teacher of Kissinger's, once described him as "an Odysseus-like polytropos, a many-sided character". Frank Shakespeare, who headed the US Information Agency under Nixon was blunter. "Kissinger can meet with six different people, smart as hell, learned, knowledgeable, experienced, of very different views, and persuade all six of them that the real Henry Kissinger is just where they are," he declared.
To understand how Kissinger views himself, it helps to look at the historical heroes he refers to in World Order. At one point he says to me, "the more you get to the outer edge of what is possible, the more you risk – you are out there alone". So who does Kissinger look to when he feels alone? Cardinal Richelieu, Louis XIII's right-hand man, Klemens von Metternich, the charismatic chancellor of the Austrian Habsburg Empire, and Otto von Bismarck, the legendary unifier of Germany. All derided for cunning and ambition, yet all able to make brilliant conceptual leaps that ultimately improved the security of the world.
Most revealing is his description of the French diplomat Talleyrand – viewed by some as the embodiment of Machiavellian duplicity. From the French Revolution onwards, he switched sides repeatedly to ensure he remained in the inner circles of power. "He started his career as Bishop of Autun," Kissinger relates, "left the church to support the revolution, abandoned the revolution to serve as Napoleon's foreign minister, abandoned Napoleon to negotiate the restoration of the French monarch, and appeared in Vienna as Louis XVIII's foreign minister. Many called Talleyrand an opportunist. Talleyrand would have argued that his goals were stability within France and peace in Europe and that he had > taken whatever opportunities were available to achieve these goals."
Certainly, as Putin goads the West with his lethal realpolitik, the Middle East and swathes of Africa witness rampant jihad, and China enters the sabre-rattling stage of its evolution, the West certainly needs someone with the ingenuity of a Talleyrand. And Kissinger, the 20th century's prime exponent of realpolitik is happy to oblige. World Order is a passionate statement of his lifelong belief that order and freedom are interdependent, and establishing long-term balance far outweighs the short-term benefits of making concessions that are popular with the electorate. He is utterly unapologetic about this – once, paraphrasing Goethe, he said, "If I had to choose between justice and disorder, on the one hand, and injustice and order, on the other, I would always choose the latter".
Certainly his views are informed by a breadth and depth of historical knowledge that rivals that of most major players in today's foreign-policy arena. Take his approach to Russia. From the 17th century to the mid-20th century, Russia proved crucial in maintaining the balance of world power – thwarting the expansionist dreams of Charles XII of Sweden, Napoleon, and Hitler. This is key to Kissinger's verdict on how we should respond to Putin's invasion of Ukraine.
"I don't agree with Putin," he declares, "but why didn't somebody, somewhere along the road, propose a solution that would have addressed both sides' concerns within the context of an independent Ukraine? When Europe said Ukraine has to choose between Europe and Russia in a commercial negotiation, [maybe] saying the opposite, saying let's do it together, might have made great progress.
"It's easy to demonise Putin," he continues. "Of course he's not easy, but one has seen that type of Russian leader before – and he's not a Hitler. One shouldn't discuss it in terms of one Russian leader. The question is how does one visualise the long-term relationship of Russia to the West at a moment when Asia is transforming itself and Islam is in permanent upheaval?"
The first building blocks of world order were established at the Peace of Westphalia – a series of treaties signed in 1648 at the end of the Thirty Years' War. Crucially, Kissinger says, "The Westphalian peace reflected a practical accommodation to reality, not a unique moral insight". In this system, the state became a fundamental building block of global order – an independent entity that would not interfere in other states' domestic affairs, yet would be prepared to check their ambitions "through a general equilibrium of power".
Whole books have attacked Kissinger's willingness to negotiate with regimes and factions with dubious human-rights records to maintain his sense of global balance, but he makes it clear that he feels he has always chosen the lesser of two evils. "I am concerned by human rights because I lived under extreme violations of them [in Nazi Germany], but when I make comments about human rights I do so as a practising foreign-policy executor," he tells me. "As a general rule I would argue that you should establish an important enough relationship with a country for it to have a stake in it, and then use that relationship to mitigate human-rights violations."
Certainly the Arab Spring has raised questions about the best way to achieve fair governance, after sadistically oppressive leaders have been overthrown to much rejoicing, only for countries to be swallowed up by sectarian warfare. "Libya was a disaster," Kissinger says. "Almost certainly more lives have been lost as a result than would have under Gaddafi – it's a horrible outcome." I tell him that I travelled in Libya while Gaddafi was in power and was disconcerted to find that I felt safer out in Tripoli at night than I had in any city in the world. He looks at me directly and nods knowingly. "It sticks in your throat when you say that," he says gravely.
He spoke out forcefully on the need to attack Isis prior to President Obama's launch of bombing raids in Iraq and Syria, but is "quite confident that we can defeat the current manifestation. Iran is much more complicated". I put it to him that if the Supreme Leader Ayatollah Khomeini is replaced by a more moderate leader such as Hojatoleslam Rafsanjani, that might lessen the threat. He shakes his head. "If Iran develops nuclear weapons, or comes close to nuclear weapons, that fact alone will shift the balance in the region, no matter how moderate the government may in the end turn out to be. Because that means that Iran defied the Security Council and prevailed in a conflict of threats with the US."
I have been warned not to raise sensitive topics with Kissinger, but he is being both charming and expansive, so I ask whether he has any regrets about the prolonged conflict in Vietnam and the secret bombing of neutral Cambodia. He dips his head. "I'm going to learn a good answer to that one day," he rumbles. Looking up he declares, "[In Vietnam] we did the best we could in a war we inherited. People forget that. The one condition that we would not yield to was to replace the government that our predecessors had established with a communist-style government. The only thing I misjudged was the possibility of a negotiated compromise. But even if I judged it correctly, how could we have acted in any other way?"
On Cambodia, he asserts that within weeks of Nixon assuming office, "The Vietnamese communists started an offensive that killed four to six hundred Americans a week, so that after a month we had lost more people in the Vietnamese offensive than we were to lose in 10 years of war in Afghanistan. Many of these casualties came from four North Vietnamese divisions that had occupied a part of Cambodian territory. Nobody has ever shown that there were any casualties in that area. I've lived with that for so many decades. I really have no regrets.
"The only regret I have is that our domestic position did not allow us to sustain the agreement that we had negotiated. The saddest day of my governmental period was the day of the evacuation of Vietnam. I believe Richard Nixon acted heroically. He withdrew 150,000 Americans every year, he stopped ground combat in 1971, and he brought it to an agreement that we believed sincerely was historic... But then aid was cut dramatically, and the possibility of American reintervention on the scale that's now taking place in Iraq by air was prohibited by Congress by special legislation."
We have been talking for 90 minutes. Around us, the good-looking young people are swinging into action for Kissinger's descent to the next floor to meet The Independent's photographer. He disappears down a corridor to the men's room to freshen up. I wait in the reception area expecting him to re-emerge, unaware of the little piece of theatre that is about to play itself out.
Seeing me waiting, one of Kissinger's assistants shakes his head, saying, "He leaves the office by his own route". He ushers me through to the lift lobby, which looks like a scene out of Alice in Wonderland with four lift entrances on one side, and one door in each of the other walls. "We never know which door he's going to come out of," he laughs. "He likes to keep us guessing."
For a moment we wait for the world's most infamous statesman, unsure, as so many throughout his career have been, from which angle he will surprise us. Then, suddenly, the door to the right of the lifts flies open. Kissinger's distinctive silhouette is etched against its frame, and he smiles at the look on our faces. "Shall we go?" he asks.
'World Order' by Henry Kissinger is out now (£25, Allen Lane)