Speculation rumbles on over the implications of targeted sanctions imposed by the U.S. and the European Union on key figures in Russian President Vladimir Putin's administration.

The latest threat is that Russia's "energy tsar" Igor Sechin may be next on the list, raising the specter of Barack Obama directly targeting Russia's energy sector. In response, Russia has been playing the China card, threatening to export its gas east in an effort to gain leverage over a European continent uncomfortably dependent on Russian supplies.

Putin's planned trip to Beijing in May is a case in point. But the past failures of Russia and China to come to an agreement to transport Siberian gas across the Chinese border suggest that Russia might be overplaying its cards.

EU and Russian leaders may not agree on much, but one thing they all understand is that an extension of sanctions to Russia's energy sector would be something of a mutual suicide pact.

An escalation of sanctions would hurt European countries — including Germany, Europe's healthiest — which as a whole are 30 percent dependent on Russian fuel. In turn, Russia exports 67 percent of its gas to Western Europe and would lose out on markets that have formed the backbone of its gas export policy for years, as well as the foundation for some expensive gas export infrastructure.

The implications for the United States are more complicated. While the domestic shale boom means the U.S. is less vulnerable to changes in global gas supply dynamics, a weakening of its allies in Europe is politically unpalatable.

China is certainly keen to secure more energy resources to satisfy its burgeoning population and industry. Affordable coal is still the dominant raw material in China's energy mix. Even among the hydrocarbons, oil has been the priority, as natural gas has been considered an expensive fuel for power generation.

China produces 4.16 million barrels of oil per day on its own soil, more than Canada does, but supply can't keep up with demand. In 2011, imported oil accounted for 54 percent of demand, and 50 percent of crude oil imports came from the turbulent Middle East.

The Chinese began importing liquefied natural gas (LNG) in 2006. Since then the government has been actively promoting its gas import policy in an effort to reduce the country's dependence on coal, boost energy security and ease the infamous smog hanging over its cities.

Russia's hopes of getting a piece of the game rest in its western Siberian gas fields, from where natural gas could be piped almost 3,000 kilometers along the Altai pipeline across Russia, Kazakhstan and Mongolia to reach Chinese customers. But unlike the extensive infrastructure (chiefly the Nord Stream and South Stream pipelines) in place or under construction to pipe Russian gas to Europe, plans for an Altai pipeline across the border China are still on the drawing board.

Russia's natural gas monopoly Gazprom has been courting the Chinese for years, but to little avail. LNG specialist Keun Wook Paik sets out four reasons why the Russians and Chinese have so far failed to agree a gas deal, and why China instead has preferred to look to gas-rich Turkmenistan, from where it can import gas along the Central Asia-China pipeline.

Firstly, unlike Central Asia, Russia has resisted Chinese requests for upstream concessions in Russian gas fields in return for gas export deals. Secondly, China can ultimately look elsewhere to Central Asia, Myanmar and even as far afield as the U.S. Thirdly, Paik highlights lack of trust between the two sides (although it is difficult to imagine greater distrust than exists between Russia and Europe today).

But the main obstacle, as with so many things, has been the price. Gazprom has insisted on getting the same prices for gas sold across its eastern border as it currently gets at its western border, and China won't budge.

While Europeans grumble at the high oil-related prices charged by Russia for its gas, China's national oil company CNPC is simply unable to increase domestic gas prices, which are centrally controlled by the Chinese National Development and Reform Commission's price department. Even if they wished to, they are unable to pass on costs to customers.

As a result, Russian and Chinese leaders have forged ahead with oil cooperation, building the ESPO pipeline from Eastern Siberia, but have left the gas issue to one side. That conversation may have to be rescued if Russia is serious about diverting exports away from European markets.

During Putin's visit to Beijing in May, the gas supply deal will be top of the agenda and Gazprom executives are optimistic. But analysts noted in 2012 that Putin had been caught on the back foot in China, and it remains to be seen whether the urgency injected by the recent sanctions will bring him to the negotiating table in a more cooperative mood.

Global gas dynamics may be changing, but Russia is still home to 17.6 percent of proven global gas reserves. Given the time scale required for Europe to cut Russia out of its gas supply chain, Putin's threat to go elsewhere with his gas is a potent one.

But China has other options, in the Middle East, Central Asia and potentially from shale once they begin to exploit their own significant unconventional resources. What's more, natural gas is more difficult to transport than crude, and putting the infrastructure in place to switch from westward exports to eastward exports is easier said than done, potentially taking years to complete.

Chinese leaders are tough negotiators and have made it clear that if they do not want to share West Siberian gas with European consumers, nor will they stand for Russia stubbornly insisting on oil-indexed gas supply contracts. Russia may withhold gas supplies from Europe, but a reorientation towards China will take a greater diplomatic effort to make progress.