NATO Secretary General Anders Fogh Rasmussen believes that Crimea's accession to Russia is part of Russia's global strategy and fears that "Russia will go beyond Crimea and the next goal will be the eastern provinces of Ukraine."

When speaking at the Brookings Institute in Washington on Wednesday, Rasmussen said that the alliance was worried that "Russia was turning its gaze further eastward and potentially preparing to seize other regions of Ukraine."

The NATO secretary general warned that if Russia continued its invasion, it would make a choice in favor of isolation in the international arena.

The events in Ukraine and Crimea's reunification with Russia have changed the world and have further consolidated the alliance between America and Europe, Rasmussen said, adding that relations between NATO and Russia can no longer remain "just business".

Today the world is different from what it was less than a month ago, Rasmussen said.