After years of involvement in the Middle East, Russia's incursion into Ukraine is forcing NATO to turn its focus back to Europe.
NATO Secretary-General Anders Fogh Rasmussen called Russian President Vladimir Putin's annexation of Crimea "the gravest threat to European security and stability since the end of the Cold War."
E.U., U.S., and NATO officials have uniformly backed Ukraine's interim government in Kiev, while decrying Russia's incursion into Crimea, the referendum to leave the Ukraine, and the resulting annexation -- which they consider illegitimate.
In the wake of Putin's action, Rasmussen said they have called off planning for what would have been a NATO-Russia mission as part of the international effort to help destroy Syria's chemical weapons. It has also suspended all staff level meetings with Russia.
And though some U.S. officials are calling for increased penalties against Russia, the NATO leader stressed that the situation doesn't have a quick fix, but said that "Europe and North America must stand together" and that he still hopes a diplomatic solution can be found.
Despite that hope, Rasmussen said Crimea "is a wake up call," adding that "we see what could be called 21st century revisionism, an attempt to turn back the clock, to draw new dividing lines on our map."
And he added that the current tensions in the Ukraine are a reminder that European security "cannot be taken for granted" and suggested that European countries should prevent further cuts to their defense budgets and work together militarily.
"We had thought that such behavior had been confined to history, but its back and its dangerous because it violates international norms of accepted behavior," Rasmussen said, referring to Russia's actions.
And even though Putin has said that he has no interest in moving his troops outside of Crimea, Rasmussen called such a possibility a "major concern" for NATO, adding that he believes that Crimea is "an element in a greater pattern, in a more long-term Russian… strategy."