Nato chief says Russia may not stop at Crimea, urges Europe to "step up"

WASHINGTON (Reuters) - The head of NATO warned on Wednesday that Russian President Vladimir Putin may not stop with the annexation of Crimea and said the crisis should serve as a "wake-up call" for European nations to bolster defence spending.

NATO Secretary-General Anders Fogh Rasmussen said Russia's move to annex Crimea following a Kremlin-backed referendum on Sunday had triggered "the gravest threat to European security and stability since the end of the Cold War."