U.S. President Barack Obama is silhouetted as he walks towards Marine One helicopter upon arriving at Amsterdam Airport Schiphol March 24, 2014. REUTERS/Peter Dejong/Pool The Obama administration is "very nervous" about Russia's recent ability to hide communications from U.S. eavesdropping equipment while commandeering Crimea and amassing troops near Ukraine's border, a U.S. official told The Wall Street Journal.

"This is uncharted territory," the official added.

The Journal reports that U.S. officials don't know how Russia hid its plans from the National Security Agency, which spies on digital and electronic communications.

Russian leaders either "deliberately avoided communicating about the invasion or simply found a way to do so without detection by the U.S.," the Journal writes.

It's also unclear if the Kremlin's new camouflage is part of a larger trend that could affect America's ability to deter Russia.

"All military combat operations depend on NSA contributions," Robert Caruso, a former assistant command security manager in the U.S. Navy and a consultant, told Business Insider when discussing documents potentially accessed by Edward Snowden. "[The Department of Defense] depends on NSA and the Defense Information Systems Agency to secure all its networks, and others networks too."

Some officials doubt that the U.S. could have done much differently as Russian special forces began a slow takeover of the strategic Black Sea peninsula, but the inability to see the developments has them concerned nonetheless.

U.S. spy agencies and the military are now implementing a "surge" of assets to expand satellite coverage and communications-interception in the region, the Journal reports.



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