The United States and European Union have reaffirmed their commitment to Nato unity and sanctions against Russia over the Ukraine crisis.
US EU relations in Trump era remain uncertain
The agreement came in a meeting between outgoing US President Barack Obama and EU leaders in Berlin.
They also criticised Russia's air strikes in Syria.
Meanwhile, the US President-elect Donald Trump and Nato's chief Jens Stoltenberg have "underlined the enduring importance of Nato."
Russia raises alarm bells for Europe in Bulgaria
They expressed the views during telephonic conversation.