In 2015, Mützenich criticized SPD "rapprochement romantics" in Germany's relationship with Russia and warned against the "misconception that old-style Ostpolitik was possible following the annexation of Crimea." In 2018, he was one of the most important critics of the decision made by Foreign Minister Heiko Maas to expel four Russian diplomats over the nerve agent attack on Sergei Skripal and his daughter Yulia, describing that the expulsion as “too hasty“ and saying there was still no conclusive proof that the Russian government was behind the poisoning.