Tensions are rising in Europe as Russia's government announced it will take countermeasures if reports of U.S. plans to upgrade nuclear capabilities in Germany are true.

A Kremlin official voiced concern over the reported U.S. plans when he spoke to reporters on Wednesday.

"Certainly, it's another, unfortunately, very serious step," Russian presidential press secretary Dmitry Peskov said. "Unfortunately, if this step is implemented -- and we can say they are confidently advancing towards its implementation, it may disrupt the strategic balance in Europe and therefore will clearly make Russia take corresponding countermeasures to re-establish the balance."

Peskov was not specific as to what exactly these countermeasures would include.

While the United States is conducting upgrades on a number of air bases in Europe, German broadcaster Frontal 21 reported on Monday that the United States was planning to deploy more bombs to Buchel Air Base in Germany.

The Buchel Air Base has kept between 10 and 20 nuclear warheads since the end of the Cold War.

Tensions between Russia and NATO countries have escalated to their most severe levels since the Cold War, stemming from Russia's annexation of Crimea, its support for militant separatists in Ukraine, and now the Kremlin's increasing intervention in Syria.

Russian president Vladimir Putin pledged support for Syrian President Bashar al-Assad's regime as it battles both the Free Syrian Army and the Islamic State, Sunni militants also identified as Daesh and by the acronyms ISIS and ISIL.

In addition to upgrading nuclear capabilities in Germany, a NATO member state, the U.S. Air Force has increased military exercises in the region.