U.S. allies in Europe allege Russia is "escalating hybrid activities" against NATO and EU nations following the severing of two data cables in the Baltic Sea. 

The declaration comes as Moscow says Ukrainian forces have fired six U.S.-made missiles into Russian territory on Tuesday. In the two days beforehand, the cables linking Finland to Germany and Sweden to Lithuania were slashed underwater, according to Reuters. 

"No one believes that these cables were cut accidentally," German Defense Minister Boris Pistorius was quoted by Reuters as saying Tuesday. "We also have to assume, without knowing it yet, that it is sabotage." 

"If Russia does not stop committing acts of sabotage in Europe, Warsaw will close the rest of its consulates in Poland," Polish Foreign Minister Radoslaw Sikorski reportedly added. 

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The foreign ministers of France, Germany, Italy, Poland, Spain and the United Kingdom issued a joint statement saying that "Moscow’s escalating hybrid activities against NATO and EU countries are... unprecedented in their variety and scale, creating significant security risks." 

However, the Tuesday statement did not directly blame Moscow for the cable damage. 

"To live up to this historic challenge, we are determined to stand united with our European and transatlantic partners to think and act big on European security," that statement also said. "European countries must play a still greater role in assuring our own security, acting alongside our transatlantic and global partners." 

The Finnish state-controlled data services provider Cinia said the severed data cable was detected Monday in the C-Lion1 cable that runs nearly 750 miles from the Finnish capital, Helsinki, to the German port city of Rostock. 

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The C-Lion1, commissioned in 2016, is Finland’s only data communications cable that runs from the Nordic country directly to central Europe, according to Finnish public broadcaster YLE. 

"A data cable between Finland and Germany was damaged and service [was] cut off. Swedish authorities are investigating as the site is in Swedish waters," a senior European official told Fox News. 

The foreign ministries of Finland and Germany said in their own joint statement that the damage comes at a time when "our European security is not only under threat from Russia‘s war of aggression against Ukraine, but also from hybrid warfare by malicious actors." 

The statement said the countries were investigating the incident, and that it was crucial that such "critical infrastructure" be safeguarded. 

"The fact that such an incident immediately raises suspicions of intentional damage speaks volumes about the volatility of our times," the two countries added. 

Fox News’ Anders Hagstrom, Jennifer Griffin and The Associated Press contributed to this report.