Russia's opposition to EU deal with Ukraine driven by historic, economic and military reasons

Russia's vigorous efforts to keep Ukraine within its orbit of influence stem from complex strategic, emotional and cultural issues. As the prospect of Ukraine signing an association agreement with the European Union wanes and Kiev focuses on improving ties with Moscow, here's a look at some of the issues at play:

HISTORY

Russia's attitude toward Ukraine is encoded in the country's name — literally, Ukraine means "at the edge" or "borderland." Most of modern-day Ukraine came under the control of the Russian czars in the 1700s after being part of the Polish-Lithuanian Commonwealth. Except for some territories' short-lived declarations of independence in the chaotic years following the Bolshevik Revolution in 1917, Ukraine remained under Moscow's control until the 1991 collapse of the Soviet Union.

More than two decades on, Russia's influence remains in the fact that surveys have shown about a third of Ukraine's citizens speak Russian exclusively or mainly in their family life — when Mykola Azarov became prime minister in 2010, one of his first promises was to work hard to learn Ukrainian.

CULTURE

Ukraine has been central to many key developments in Russian culture. Kievan Rus — a loose federation of Slavic tribes centered in Kiev — was the regional power in the 9th to 12th centuries, when Moscow was a mere settlement. Its ruler, Prince Vladimir, brought Christianity to the region, laying the foundation for the Russian Orthodox Church, now the largest Orthodox denomination. Some of the most prominent names in Russian literature have their roots in Ukraine, including Nikolai Gogol and Mikhail Bulgakov.

FEAR OF WESTERN EXPANSION

President Vladimir Putin saw Ukraine's 2004 Orange Revolution as a Western plot to expand into Russia's historic turf. Putin has also criticized the proposed political association and free trade deal between the EU and Ukraine as yet another attempt to encroach into what Russia sees as its traditional sphere of influence. He has accused the EU of "pressure and blackmail" of Ukraine.

As Kiev intensified talks with the EU in recent months, Russia restricted imports of Ukrainian goods, such as steel and chocolates, which Azarov claims have reduced this year's exports by $6.5 billion. Russia has also warned it would slap higher taxes on all Ukrainian exports it the country joins the EU.

If Ukraine signs the EU deal despite Russia's stumbling blocks, it would represent a big blow to Putin.

MAJOR CONDUIT FOR GAS SUPPLIES TO THE WEST

Ukraine serves as the main conduit for Russia's natural gas exports to Europe, and the pricing disputes between the two countries have led to shutdowns in many parts of the continent.

Russia has lobbied for years to acquire a controlling stake in Ukraine's pipeline network, but Kiev has continuously rebuffed such overtures. Moscow has also sought to reduce its dependence on Ukraine's transit capacity by building an alternate gas pipeline under the Baltic Sea and is also planning another one under the Black Sea. But Ukraine still accounts for the bulk of export supplies.

CLOSE INDUSTRIAL TIES

When Ukraine was part of the Soviet Union, it was home to some of its leading industrial plants specializing in metals, cars, shipbuilding, aviation and missiles among other products. Some of these plants have been badly crippled by an economic meltdown that followed the 1991 collapse of the Soviet Union, but many have managed to stay afloat.

Russia has continued to depend on Ukrainian manufacturers for aircraft and rocket engines, turbines, pumps and numerous industrial components and manufacturing tools. In particular, some of the Soviet-built intercontinental ballistic missiles that still form the core of Russia's strategic nuclear forces were manufactured in Ukraine and require spares and maintenance that can only be provided by Ukrainian factories. Russian-built combat helicopters also continue to rely on Ukrainian-built engines.

As part of its efforts to prevent Ukraine from signing the deal with the EU, the Kremlin has argued that the agreement would force Russia to phase out industrial cooperation — a move that could weigh heavily on Ukraine's industrial base.

KEY NAVY BASE

Ukraine hosts the Russian Black Sea Fleet base in the Crimean port of Sevastopol. While the Black Sea Fleet is relatively small compared to other Russian navy forces, its ships have played an important role in Russia's efforts to project its power worldwide. Some of them recently sailed to Syria's shores.

The Black Sea Fleet, which has been involved in a number of historic battles over the centuries, also serves as an important symbol of Russian national pride.

In 2010, President Viktor Yanukovych signed a deal with Russia extending its lease on the base until 2042. Russia has been slow to build an alternate base on its own Black Sea coast, so a Ukraine reversal could in theory leave the Russian navy stranded.