Russian President Vladimir Putin said making Ukraine choose between Russia and the EU would split it in two. Poroshenko told Amanpour that Friday's negotiations, which will include European officials, must show some progress before his unilateral cease-fire expires at the end of the day. Ukrainian President Petro Poroshenko is entering into a trade agreement with the European Union on Friday that has already sparked a rebellion, toppled a president and ignited an armed conflict with pro-Russia separatists. "Ukraine would become a conduit for relatively cheap and much-higher-quality European goods, which would force the Russian state to step in and subsidize inefficient Russian producers more than they are already doing," Rojansky said. There's a lot of concern about what could happen in eastern Ukraine - the ceasefire announced a few days ago by Mr Poroshenko, and the ceasefire announced by armed separatist rebels, is due to expire today. The fighting in eastern Ukraine's Donetsk and Luhansk regions is widely believed to be supported by Moscow, as many of the separatist leaders are Russian citizens and veterans of other post-Soviet regional conflicts.  Story highlights CNN EXCLUSIVE: Christiane Amanpour interviews Ukrainian President Petro Poroshenko 
 
 Poroshenko says a peace deal can come within months or even weeks 
 
 Russian President Vladimir Putin can be pragmatic or emotional, Poroshenko says 
 
 Ukraine will sign a cooperation agreement with the European Union on Friday 
 
 New Ukrainian President Petro Poroshenko says peace is possible if Russian President Vladimir Putin is in the right mood. The Organization for Security and Co-operation in Europe, which operates a special monitoring mission in eastern Ukraine, said Thursday that four members of a Donetsk-based team of OSCE monitors apparently held by separatists had been released.
– It's official: The Ukraine has signed a free trade deal with the European Union, the BBC reports—the same free trade deal that sparked the protests that led to the current crisis. President Petro Poroshenko called the deal the most historic moment for Ukraine since it gained independence in 1991, while a none-too-pleased Vladimir Putin warned that Ukraine was being pushed into "an artificial choice between Russia and the EU" and a "painful internal conflict." A senior Kremlin adviser even called Poroshenko a "Nazi." In practical terms the deal, which was also signed by Georgia and Moldova, changes little "except Vladimir Putin's blood pressure," quips the LA Times. Russia will still be a key trading partner for Ukraine, thanks to their deep military-industrial complex ties. But politically Putin hates seeing former Soviet states drawn into closer alliances with the West. There's also some concern, a BBC analyst says, that Russia could be flooded with cheap EU goods. In other Ukraine developments: The current ceasefire is set to expire today. Putin is calling for a long-term ceasefire to replace it, and talks to institute one are planned for today. Poroshenko took his own shot at Putin, telling CNN yesterday that peace depended on the Russian leader's mercurial mood. "Sometimes, the position of Mr. Putin is quite pragmatic, sometimes it is very emotional," he said, adding, "I'm ready to make a peace deal with anybody."