The Russian president sees his “Eurasian Union”, in which Ukraine would play a central role, as a future rival to China, the United States and the European Union. Some say he sees it as the president’s personal political legacy – a strong force emerging from the ashes of the old Soviet Union.

“The Eurasian Union is a very important project for Putin. Without Ukraine, he will lose all enthusiasm for it,” said Gleb Pavlovsky, a former Kremlin spin doctor who has also worked in Ukraine. “Without Ukraine, Putin’s project is impossible.”

Putin also hopes to woo several other former Soviet republics that were being courted by EU leaders at a summit in Lithuania on Friday. But none is more important to Putin than Ukraine, a huge market and the cradle of Russian civilization.

The opposition-minded Russian newspaper Novaya Gazeta described the situation as a love triangle in which Ukraine was a cheating husband, the EU an attractive mistress and Russia an angry wife. Who would win out in the end was unclear.