WASHINGTON - Russia is refusing to back down in the face of U.S. and European sanctions imposed over Moscow's annexation of Crimea.  Russia's latest actions have touched off a new round of worry for Russia's Western-leaning neighbors and more warnings from Washington.

As Ukrainian naval forces looked on, Russia moved in pro-Russian militias.  They stormed the gates of Ukraine's naval headquarters and put new security in place.

In Washington, NATO Secretary General Anders Fogh Rasmussen called Russia's aggression a "wake-up call."

"This is the gravest threat to European security and stability since the end of the Cold War," he said.

Rasmussen compared Russia to a bully and said Moscow's actions have forced NATO to suspend planning a joint escort mission to destroy Syria's chemical weapons.  

And while NATO is open to dialogue, he said the security of member states is paramount.

"The North Atlantic alliance has not wavered and it will not waiver," Rasmussen said.

It was a message U.S. Vice President Joe Biden also delivered, earlier, in Lithuania, to Russia's nervous Baltic neighbors.

"As long as Russia continues on this dark path, they will face increasing political and economic isolation," he said.

Samantha Power, U.S. Ambassador to the United Nati
Samantha Power, U.S. Ambassador to the United Nations, speaks to a meeting of the United Nations Security Council to discuss the situation in Ukraine, March 19, 2014, at U.N. headquarters in New York.

At a meeting of the U.N. Security Council, U.S. Ambassador Samantha Power took another verbal shot.

"Russia is known for its literary greatness and what you just heard from the Russian ambassador showed more imagination than Tolstoy or Chekhov," she said.

And she accused Russia of "rewriting" its borders.

A White House spokesman also warned Wednesday that existing sanctions, and new sanctions in the works, would ensure Russia pays a high price.

But Russia remains resolute, its constitutional court Wednesday approving legislation that allowed Russian President Vladimir Putin to put the finishing touches on the annexation of Crimea.

Meanwhile, Russian lawmakers brushed aside threats from the West.

"Any sanctions that they might impose against certain Russian officials is just a tiny vengeance and it won't achieve its goal,'' said Duma Deputy Speaker Sergei Zheleznyak.

Russia is cementing its hold on Crimea both with force and with symbols.  New lettering in Russian on the facade of the Crimean parliament building is a sign of the times.