Who's next?

Baltic countries

Estonia, Latvia and Lithuania are often called the Baltic countries because of their location on the eastern shores of the Baltic Sea in northeastern Europe. They were annexed by the Soviet Union in 1940 but were among the first states to break away from the crumbling union in 1991, declaring independence and forging alliances with the West. Today, the Baltic states are members of both the European Union and NATO. Russia's shadow still hangs over the region, however, which remains heavily reliant on Russian oil and gas.

Estonia: On the northeastern edge of Europe, roughly a quarter of Estonia's 1.3 million citizens are ethnic Russians. The country is heavily forested, has more than 1,500 islands and is a springboard for Internet entrepreneurs.

Latvia: Slightly larger, Latvia underwent heavy industrialization under Soviet rule, attracting a huge influx of immigrants from Russia. Of the country's 2 million people, more than a quarter speak Russian today. Beyond some manufacturing, its economy is based largely on agriculture, fishing and forestry.

Lithuania: The first Soviet republic to declare independence from the USSR, Lithuania, with a population of 3 million, has maintained tight economic ties to its neighbor ever since: Today, Russia, its top trading partner, accounts for nearly 18 percent of Lithuanian exports. Russia also keeps a particularly close eye on Lithuania, which shares a border with the Russian exclave of Kaliningrad.

EU borderlands

Continuing south, Belarus, Ukraine and Moldova now form a buffer between the EU, which has expanded to include Central and Eastern European countries in recent years, and Russia. Not surprisingly, all three former Soviet-bloc countries - which have perhaps endured their independence as much as they have relished it - are also at the center of a tug-of-war between the EU and Russia. While Belarus has already joined Russia's Customs Union, Ukraine and Moldova are being heavily courted by the EU.

Belarus: Following the collapse of the Soviet Union, Belarus became independent in 1991. Since 1994, the country has been ruled with an iron fist by President Alexander Lukashenko, who continues to oppose privatization of state enterprises (private business is virtually non-existent) and is keen to develop closer ties with Russia. Belarus remains heavily dependent on Russia for its own energy needs, and a significant proportion of Russian oil and gas exports to Europe pass through it.

Ukraine: Plenty of eyes are now centered on Ukraine after months-long protests, the ouster of its president, a new government and a secession vote in Crimea to join Russia. Ukraine has a long history of being subjugated by foreign powers, a fact reflected in its name, which many scholars interpret as “borderland.” The country remains deeply divided by language, history and politics. About a third of the nation speaks Russian as its native language, and the Russian-speaking eastern half of the country, unsurprisingly, is more pro-Russian. Ukraine is an important source of food for Russia and a transit hub for Russian energy exports. The country is also a vital supplier of water and electricity to Crimea.

Moldova: Moldova, which has a population of about 4 million people, was part of Romania until it was annexed by the Soviet Union in 1940. It has also long faced its own secessionist threats, particularly in its Transnistria and Gagauzia regions. Transnistria is a narrow breakaway state in eastern Moldova on the border of Ukraine. It consists of about 200,000 people, a mix of ethnic Russians, Ukrainians and Moldovans. It proclaimed its independence from Moldova in 1990, one year before the Soviet Union dissolved, amid fears Moldova would rejoin Romania. Russia subsidizes Transnistrians' pensions and maintains troops in the territory. In a disputed 2006 referendum, 97 percent of the population voted in favor of joining the Russian Federation.

Gagauzia is another autonomous region in Moldovan territory under Russian influence. It has a population of about 155,000, most of them a Turkic-speaking ethnic group known as the Gagauz. It held a referendum earlier this year calling for closer ties with Russia, including integration into Russian President Vladimir Putin's Eurasian Union. Nearly 99 percent of those voting in the referendum rejected an association deal with the EU.

The EU has been developing an increasingly close relationship with Moldova, including advanced talks on an EU Association Agreement. Russia has placed pressure on the Moldovan economy to join its customs union by boycotting Moldovan wine and agricultural exports, among other measures.

Caucasus

The Caucasus is a region at the border of Europe and Asia, considered one of the most linguistically and culturally diverse regions on earth. It's also a hotbed of tension. In the post-Soviet era, most of the economies in the region - with the exception of Azerbaijan, thanks to oil - have performed dismally, creating huge social unrest. Russia still wields significant influence in the region. Among the most serious flashpoints: Abkhazia, South Ossetia, Ingushetia, Chechnya and Dagestan.

Abkhazia: In 1999, Abkhazia declared independence from Georgia, which still regards it as a breakaway region. Its fight for independence from Georgia since the collapse of the Soviet Union, however, has reduced its economy to ruins. Russian investment has been flowing into Abkhazia more recently as Moscow seeks to increase its influence there. Russia has had anti-aircraft missiles stationed in Abkhazia since 2010. Roughly a quarter of a million people live in Abkhazia.

South Ossetia: Recognized as an independent state by Russia after its 2008 war with neighboring Georgia, South Ossetia today is an isolated enclave heavily reliant on funds from Moscow. Unemployment is high - and so are prices. For years, South Ossetia has lobbied Russia to absorb it, voting for annexation as far back as 1992. Roughly 70,000 live there.

Ingushetia: Ingushetia is a republic within Russia, which theoretically means its 400,000-plus citizens have wide-ranging autonomy. The overwhelming majority are Muslim, and clan links are an integral part of society.

Chechnya: In 1991, Chechnya declared independence from Russia. Three years later, the Kremlin dispatched troops to restore its authority. The move sparked the first Chechen war, which ended in a humiliating defeat for Russia in 1996. But in 1999, Russian troops returned. Unemployment and poverty are endemic to Chechnya despite huge funding Moscow has provided for reconstruction. Roughly 1.25 million people live there.

Dagestan: Like Ingushetia and Chechnya, Dagestan is a Russian federal subject, or republic. Its population of nearly 3 million is predominantly Muslim. Although only 3.5 percent of the population is ethnic Russian, the primary official language is Russian. The republic has oil and gas reserves and also fisheries. Since the fall of the Soviet Union, the republic's authorities have been largely regarded as loyal to the Kremlin - but also as highly corrupt.