Ukraine's economic woes are deepening. Just on Tuesday, Aleksei B. Miller, the chief executive of the giant Russian energy company, Gazprom, appeared to escalate the standoff by threatening to invoke a clause in the Ukrainian gas contract demanding payment in advance for winter heating.
"This is a dire state of affairs," Mr. Miller said in a statement, whose tone recalled warnings that Gazprom had issued before shutting off gas to Ukraine in energy embargoes in 2006 and 2009.
The Customs Union of Russia, Belarus and Kazakhstan, a pet project of President Vladimir V. Putin, will never truly rival the E.U. The output of the Customs Union states was $2.3 trillion in 2012, compared to $16.6 trillion for the European Union, according to the International Monetary Fund. Ukraine's economic output of $176 billion last year would only modestly bolster the Russian bloc.
But bulking up with Ukraine's 46 million consumers would narrow the population gap with the European Union. A Customs Union that included Ukraine would have a total population of about 215 million people, compared to the total population of the 27 nations in the European Union of about 501 million people.
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"Putin and his team are pressuring Ukraine because Eurasian integration cannot happen without Ukraine," Mikhail Pogrebinsky, a political analyst in Kiev, said of the tactics such as those being brought to bear on Roshen.
Russian officials have suggested they are merely conveying to business owners in the region what loss of market access would result if their country's officials choose to remain outside the Russian-backed trade group.
With that sentiment conveyed, what is known here as the chocolate war began.
The company, one of Eastern Europe's largest candy makers, had sales of $1.2 billion in 2012, up from $1 billion the year before. The company exports 320 different types of candies to 30 countries, but specializes in treats preferred by residents of the former Soviet Union.
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Until the ban, Roshen exported 8,000 tons of sweets to Russia monthly, even during the world recession. "Recession affects real estate but not chocolate," Mr. Moskalevskyi, the director, said. While the company has been able to redirect some chocolate to Ukraine, the drop in output shows Ukrainians can't eat it all.
Ukrainian businesses are also squeezed from the other side. The European Union's high tariffs on agricultural goods such as those contained in cakes and chocolate all but rules out sales to Western Europe, at least until any easing of tariffs takes place under the Association Agreement. Also, European confectionery companies and candy makers have themselves been investing in Russia, seen as having a higher potential for growth than Europe, which is saturated with sweets, Mr. Moskalevskyi said.