The ancient Chinese proverb "The enemy of my enemy is my friend" has been a cornerstone of realist statecraft since the dawn of, well, realist statecraft. For example, Britain formed an alliance with its long-standing enemy, France, in order to counteract the Germans during the First World War. Responding to criticism of his Second World War allegiance to Stalin's Soviet Union, Winston Churchill claimed that "if Hitler invaded hell, I would at least make positive reference to the devil in the House of Commons".
Comparatively, during the cold war, liberal-democratic states often formed alliances with non-communist dictators, such as Mobutu of Zaire. The Soviet Union provided financial assistance to a handful of anti-communist states to strengthen their cold war sphere of influence. The US supported the Afghan mujahedin during the ten-year Soviet occupation of Afghanistan.
However, the principle alone may serve as a weak basis for alliance: after the break-up of the Soviet Union some of the mujahedin spawned the Taliban and turned against the United States.
Now, in a twist of fate, a partnership between Russia and the United States is materialising, based on this timeless principle.
Last week, Mikhail Gorbachev declared that, like the Soviet Union 21 years earlier, Nato would not be able to beat the Taliban. The 79-year-old former president claimed that no feasible increase in troop numbers could ever improve the situation for the US, and that Afghanistan is at risk of turning into "another Vietnam".
It seems that the Russians, thus far passive observers of the war raging in their backyard, have decided to contribute their topographical expertise in the area. Ironically, both countries are said to be articulating the definition of the alliance at Nato's Lisbon Summit on 19 November. This has been received with speculative cries in the field of international relations, Foreign Policy dubbing it "Nato 3.0".
Despite the cessation of the cold war, Russia has not extended its hand to the US in this way before. Nonetheless, Russia has not necessarily offered a hand of friendship, and there is speculation that Moscow's concerns are solely interest-fuelled.
It has been widely reported that the Russians agreed to assist the Americans with their operations in Afghanistan because Russia has one of the worst heroin addiction rates in the world. Its two million heroin addicts consume 21 per cent of the world's supply, and Russia blames the severity of the problem on the US's failure to spray poppy fields in Afghanistan.
Last Friday, Moscow announced that a joint narcotics raid with US forces had destroyed four drug laboratories and one tonne of heroin.
This sudden change on the international playing field invites a host of fresh and important questions for foreign policy experts. If Russia and the US achieve their common goal, will the alliance between them survive? Do these former rivals share enough common ground to be considered friends? And what is the true nature of this politically significant alliance?