By Phil Stewart
WASHINGTON, March 19 (Reuters) - NATO Secretary-General Anders Fogh Rasmussen accused Russia on Wednesday of tossing out international rules in an attempt to "redraw the map of Europe," as he called the Ukraine crisis NATO's most pressing security challenge.
"We have seen Russia rip up the international rule book, trying to redraw the map of Europe, and creating, in just a few weeks, the most serious security crisis since the end of the Cold War," Rasmussen told a forum at Georgetown University during a trip to Washington.
"This sort of behavior goes against international norms, and it simply has no place in the 21st century."
Rasmussen had dinner on Tuesday at the Pentagon with U.S. Defense Secretary Chuck Hagel, Secretary of State John Kerry and White House national security adviser Susan Rice.
A U.S. defense official said the conversation focused on Ukraine, the impact of the crisis on the alliance, NATO-Russian cooperation and European security.
"The crisis in Ukraine is the most pressing security challenge right now, also because it goes to the heart of what NATO is about," Rasmussen said at Georgetown, adding the alliance's stated aim is to strengthen security and stability in the Euro-Atlantic region.
"What we see in Crimea is a threat to security and stability in the Euro-Atlantic area."
Russian President Vladimir Putin, ignoring calls from the United States and European Union, has moved to annex Crimea into Russia following a Kremlin-backed referendum there.
Since the end of the Cold War, NATO has shifted its attention to Afghanistan, Kosovo and counter-piracy operations off the coast of Somalia, as well as Libya during its 2011 civil war.
But by the time NATO government leaders meet in September in Wales, some people believe, their focus will have returned to deterring Moscow. That could also lead to a modest reversal of years of European defense cuts.
U.S. Vice President Joe Biden said in Warsaw on Tuesday the United States may run more ground and naval military exercises to help Baltic states near Russia beef up their capacity after what he called Russian President Vladimir Putin's "land grab" in Ukraine.
Any additional military exercises in the Baltics would build on measures already taken, officials said. The Pentagon increased the number of U.S. aircraft in regular NATO air patrols over the Baltics, and it beefed up a previously planned training exercise with the Polish air force.
Asked by Reuters about any additional NATO exercises, Rasmussen said: "That's one of the possibilities."
But he also noted plans had already been under way to step up exercises in the coming years.
"And of course, some of these exercises could take place on the territory of Eastern allies," he said. (Reporting by Phil Stewart; additional reporting by Adrian Croft and Peter Apps; Editing by Warren Strobel and Mohammad Zargham)