The city that may be Ukraine's line in the sand

Relatives and mourners of 18-year old Vadim Papura, a pro-Russian activist killed after he jumped off from the Odessa Trade Union building on May 2, 2014, attend his funeral four days later.
Veli Gurgah | Anadolu Agency | Getty Images
Relatives and mourners of 18-year old Vadim Papura, a pro-Russian activist killed after he jumped off from the Odessa Trade Union building on May 2, 2014, attend his funeral four days later.

Violent clashes have become a daily occurrence in eastern Ukraine ahead of the country's May 25 presidential election, and pro-Russian forces have been winning there. However, the southwestern port city of Odessa may be the proverbial line in the sand between the two sides.

Fighting in the "Jewel of Ukraine" this month marked the first time major clashes in a city that has seen significant—and so far successful—pushback against pro-Russian groups. Pro-Ukraine rioters killed at least 42 of their opponents in fighting and a fire Odessa earlier this month.

Odessa is more than 425 miles (about 700 kilometers) from Donetsk in eastern Ukraine, where pro-Russian forces have commandeered whole cities and this weekend held ad hoc referendums on independence.

It's Ukraine's biggest Black Sea port, even larger than Sevastopol in Crimea, which Russia annexed in March. Odessa lies in a region that forms Ukraine's maritime coastline and is of utmost importance to it economically.

"Ukraine without Odessa is effectively a landlocked country," said Matthew Rojansky, director of the Kennan Institute.

Read MoreMeet the beneficiaries of the crisis in Ukraine

Alexander Kliment, director of Russia and Emerging Market research at Eurasia Group, said unrest into those southern regions of the country would substantially weaken the Ukrainian government's legitimacy and security, though he thinks things are not yet at that point.

"If anything, the Odessa events showed that pro-Russian forces might have a significantly harder time gaining grassroots support there than they did in the eastern regions, which are closer, geographically, economically and culturally, to the Russian orbit," Kliment said.

A Stratfor report last week highlighted the difference between unrest in the eastern parts of Ukraine and in Odessa, the scene of the 1905 mutiny by the crew of the battleship Potemkin against the czar.

"Odessa, whose historical significance resonates deeply in Russia and whose port is vital to Ukraine's economic livelihood, could be exploited by Moscow as the Russians look for opportunities to cripple Kiev," the report said.

Read MoreRebels declare victory in East Ukraine vote on self-rule

Stratfor analysts also point out that because of the resistance in Odessa on the part of pro-Ukrainian forces, there would be much more risk for Russia if it decided to destabilize Odessa.

—By CNBC's Dina Gusovsky

Currencies Explained

Economy Explained

  • Economic data can be like the porridge of a certain fairy tale: Too hot, too cold, or just right.

  • Sequestration is a fiscal policy procedure adopted by Congress to deal with the federal budget deficit.

  • Americans often check their receipts to make sure they've bought everything they need, and probably to see if what they paid this time is any different from the last trip. The government does the same with the Consumer Price Index. Here are the details. 

CNBC Explains

  • What is asset allocation? Is there a mix of securities that can perfect portfolio diversification? CNBC explains.

  • Traders on the floor of the New York Stock Exchange.

    Capitulation is a way to describe a surrender between armies, but it's also a form of 'giving up' on the stock market. So, what is capitulation when it's used on Wall Street? What does it signify? CNBC explains.

  • Alibaba founder Jack Ma gives a thumbs-up as he arrives to speak to investors at an initial public offering road show in Singapore Sept. 16, 2014.

    Alibaba's long-awaited IPO is finally around the corner, making this a good time to take a look at just how an IPO works.

Latest Special Reports

  • With the world becoming more interconnected, it’s getting harder to anticipate and manage global risks. We take a look at some of the biggest risks and ways to mitigate them.

  • From family-run companies to public companies with family ownership, we tackle challenges and rewards facing family businesses.

  • Inside the market's biggest sectors with a look at the trends, companies and trades netting profits for investors.