CNN —
US military bases across Europe were placed on heightened alert last week for the first time in a decade after the US received intelligence that Russian-backed forces were considering sabotaging US personnel and facilities, multiple sources told CNN.
Intelligence received by the United States suggests Russia has included U.S. military bases and personnel as options for proxy attacks, similar to plots carried out and thwarted across Europe in recent months, the people said.
In April, two Russians of German descent were arrested on suspicion of planning bomb and arson attacks on US military facilities and other targets on behalf of Russia.
The previously unreported information, received by the U.S. within the past two weeks, was deemed alarming enough to implement additional security protocols, according to the sources. Several U.S. military bases in Europe have raised their alert level to “Charlie,” which applies “when an incident occurs or information is received indicating any type of terrorist act or attack targeting personnel or facilities,” the Army said.
A senior NATO official said Tuesday that the alliance has “significantly increased” intelligence sharing about “Russia's covert sabotage campaign.” The campaign has become increasingly bold and aggressive in recent months amid ongoing Western elections, presenting a “perfect opportunity” for Russia to try to undermine public support for Ukraine, the official said.
U.S. European Command declined to comment directly on the reasons for last week's force protection changes, but spokesman Gen. Dan Day said, “Our increased vigilance is not related to any single threat, but rather to a combination of factors that potentially impact the safety and security of U.S. forces in the European theater.”
The threat of Russian-backed sabotage has become particularly acute in recent months after a series of arson and bombing plots across Europe that European security officials blame on Russia, including fires and explosions in Riga, Latvia; London; Warsaw, Poland; Prague, Czech Republic; and Paris.
In London, several men were charged in March with working with Russian intelligence to set fire to a warehouse linked to Ukraine. Poland is investigating whether an arson attack that destroyed Warsaw's largest shopping mall in May had Russian links, and its prime minister said in May that nine people had been arrested for Russian-linked sabotage. And last month, French authorities arrested a Ukrainian man of Russian descent who they said was building bombs as part of a sabotage campaign orchestrated by Moscow.
Russian officials say Russia believes outsourcing attacks to local forces allows it to wage a hybrid war below the threshold of international conflict, but NATO officials say the sabotage operations have become increasingly bold and aggressive.
“What we're seeing right now is a more coordinated, more aggressive effort than we've seen since the Cold War,” the official said Tuesday. “We're seeing sabotage, assassination attempts, arson – actual loss of life.”
This story has been updated with additional information.
CNN's Katie Beau Lillis contributed reporting.
