Russia's military moves in Ukraine "shatter the myth" that the end of the Cold War meant an end to insecurity, at least in Europe, Defense Secretary Chuck Hagel said Friday.
Amid worries in Europe that Russia may be preparing for broader aggression, Hagel said the NATO alliance "must stand ready to revisit the basic principles underlying its relationship with Russia." He did not elaborate.
Hagel renewed a familiar U.S. call for increased defense spending by European members of NATO, saying that even a united Europe still faces great dangers.
"While we must continue to build a more peaceful and prosperous global order, there is no postmodern refuge immune to the threat of military force," Hagel said in a speech at the Woodrow Wilson International Center for Scholars. "And we cannot take for granted -- even in Europe -- that peace is underwritten by the credible deterrent of military power."
Hagel said NATO members need to boost their defense investment because over the long run Russia will test the purpose, stamina and commitment of the 28-nation U.S.-led alliance.
"In recent years, one of the biggest obstacles to alliance investment has been a sense that the end of the Cold War ushered in the `end of history' and an end to insecurity -- at least in Europe -- from aggression by nation-states. Russia's actions in Ukraine shatter that myth and usher in "bracing new realities," Hagel said.
He dismissed the notion advanced by some critics that U.S. support for the expansion of NATO, starting in the late 1990s, is responsible for Russia's recent aggressive moves. Poland and other central and eastern European nations that once were in the Soviet sphere of influence are now NATO members.
Looking beyond the military aspects of European security, Hagel said the U.S. and Europe should work together to "blunt Russia's coercive energy policies."
He said the U.S. Energy Department has conditionally approved export permits for U.S. liquefied natural gas that add up to more than half of Europe's gas imports from Russia.
He called for the inclusion of budget officials at a future NATO defense ministers meeting focused on ways to break the pattern of steadily declining defense budgets among European member states.
NATO's defense ministers, including Hagel, are scheduled to meet in June, followed by a gathering of alliance foreign ministers, including Secretary of State John Kerry. President Barack Obama is due to attend a NATO summit in Wales in September.
A key challenge for the alliance in the weeks ahead will be finding a unified position on the nature of the Russian threat and how to respond over time.