European Union leaders are expected to discuss tense relations with Russia during a summit starting on December 18 in Brussels.
No new sanctions are expected to be decided at the two-day summit, as the EU "is not in a hardening mindset," one diplomat told AFP news agency.
Another said, "We don't want to provoke Putin too much."
The EU and United States have imposed sanctions on Russia in response to Moscow's actions in Ukraine, where pro-government forces have been battling pro-Russian separatists since April.
EU leaders will also discuss a 315 billion euro ($392 billion) investment plan aimed at helping revive growth in the EU.
The summit will be the first one led by the newly appointed European Council president, former Polish Prime Minister Donald Tusk.
