BRUSSELS (Reuters) - Russia's approach to Ukraine and to the European Union is a challenge to the 28-nation bloc, which does not make European leaders too optimistic, but rather realistic, the new president of the European Council, Donald Tusk, said on Thursday.
"In fact Russia is today our strategic problem, not Ukraine," the former Polish prime minister told a news conference after chairing a summit at which EU leaders discussed Russia and its involvement in the conflict in eastern Ukraine.
"The biggest challenge today is the Russian approach, not only to Ukraine but also to the EU," Tusk said.
He said Moscow's "aggressive" stance towards Ukraine and the EU had been triggered by the decision of Kiev to sign a trade and cooperation agreement with the EU.
"Today we are maybe not too optimistic, but we have to be realistic, not optimistic," Tusk added.
(Reporting By Jan Strupczewski and Paul Taylor)