The world is witnessing the most important geopolitical events since the Sept 11 attacks in the United States in 2001. This can be seen in Russia's annexation of Crimea, the imposition of American and European sanctions, and the potential for more escalation in Ukraine.
Developments in Ukraine mark a tipping point. Relations between Washington and Moscow were already strained. But with Russia now suspended from the Group of Eight leading industrialised countries, and more sanctions likely, relations are now fully broken.
Various forms of East-West conflict are inevitable, with implications for Europe's security, Russia's stability, the future of the European Union and Nato, and global energy markets.
But though tensions are here to stay and will probably get worse, this is not a new Cold War. Nor will it become one. There are several reasons for this.
First, Russia has neither powerful friends nor the power to win new ones. When the United Nations General Assembly voted on the legitimacy of Russia's annexation of Crimea, just 10 countries sided with Russia. Support came from neighbours that Russia can coerce (Armenia and Belarus) and rogue states without international influence (Cuba, North Korea, Sudan, Syria and Zimbabwe).
Throw in traditionally sympathetic Latin Americans (Venezuela, Bolivia and Nicaragua) and it's clear that Russia lacks the Soviet Union's ideological appeal. Russia's allies are more aligned in their distaste for the established global order than in any alternative organising principle that Moscow can offer.
In addition, Russia's gross domestic product grew by just 1.3 per cent last year. And the Russian economy's increasing dependence on exported natural resources ensures that growth won't improve without an unlikely spike in global energy prices.
In 2007, Russia needed a Brent oil price of US$34 per barrel to balance its federal budget. Five years later, that figure stood at US$117. Last year, oil and gas comprised about half of Russia's government revenue.
Making matters worse, Russia's economy is controlled by a small elite that depends on President Vladimir Putin's favour. More than one-third of Russia's total household wealth is in the hands of the country's richest 110 people.
Despite its nuclear weapons, which are subject to the same rules of mutually assured destruction that bound US and Soviet weapons, Russia also lacks the Soviet Union's military capability. Today, the US spends about eight times the amount Russia can provide for its military. Russia has the muscle to make mischief for its neighbours, but it cannot project power on a Cold War scale.