BRUSSELS -- It was supposed to be a done deal: European Union envoys had been expected to approve a six-month extension of sanctions against Russia over its interference in Ukraine, as agreed by EU leaders last month.

But the Italian ambassador upended that plan at a meeting on December 9, telling the others that Rome wanted more debate on the matter.

A high-ranking EU diplomat told RFE/RL that EU ambassadors would not discuss the sanctions at their December 10 meeting. That means the issue is unlikely to be resolved this week, dragging the discussion closer to an EU summit on December 17-18, the holiday recess, and the January 31 deadline for a final agreement to prolong the sanctions through July 31, 2016.

So far only Rome has spoken out, but diplomats suspect countries such as Hungary, Austria, Greece, and Cyprus may be in the same camp.

Italian Prime Minister Matteo Renzi was among the leaders who agreed on the sanctions extension at a meeting on the sidelines of a G20 summit in Turkey on November 16 -- so why the unexpected change of heart?

EU sources say that Renzi may have been driven by one of the following motives, or a combination of all three:

1. He wants to put pressure on EU member states from the east to be more helpful on another crucial issue facing the 28-member grouping -- migrants -- in the run-up to the EU summit next week.

2. He wants to show the Italian business community and Russia -- whose foreign minister, Sergei Lavrov, is visiting Italy on December 10-11 -- that he is fighting to the end, not just giving in to the EU majority.

3. He dislikes European Council President Donald Tusk and wants to annoy him, knowing that the former Polish prime minister cares deeply about the issue and is determined to keep sanctions against Russia in place.