The world is “on the brink of a new Cold War” because of the crisis in Ukraine, former Soviet Union leader Mikhail Gorbachev warned Saturday during a speech commemorating the 25th anniversary of the fall of the Berlin Wall. He said Western countries “succumbed to triumphalism” after the Soviet Union’s collapse, contributing to the global powers’ difficulties in resolving conflicts in the Middle East and Ukraine.

“Bloodshed in Europe and the Middle East against the backdrop of a breakdown in dialogue between the major powers is of enormous concern,” BBC News quoted Gorbachev as saying during an event at Berlin’s Brandenburg Gate.

While Russia and Western European countries had rebuilt their trust over the past two decades, Gorbachev said that this trust had “collapsed” in the past few months, Deutsche Welle reported. He called on the U.S. and Western Europe to lift economic sanctions on Russia officials and engage in dialogue with Moscow, RIA Novosti said.

Europe is becoming an “arena of political upheaval, of competition for the spheres of influence, and finally of military conduct,” Gorbachev said, referring to the expansion of NATO and military involvement in Syria and Iraq. Meanwhile, the crisis in Ukraine was a “blister turning into a bleeding, festering wound,” he said.

Gorbachev, 83, led the Soviet Union in the late 1980s and is credited with ushering in reforms that led to the eventual collapse of the communist bloc in Eastern Europe. A sobering interlude in contrast to the otherwise celebratory mood in Berlin, his speech came on the heels on comments by the Dutch foreign minister that indicated some or all of the bodies of the remaining victims of Malaysian Airlines Flight 17, shot down over Ukraine in July, might never be recovered. The remains of nine victims have yet to be recovered.

The U.S. and Western European countries have accused pro-Russian separatists in eastern Ukraine of shooting down the plane, while Russia has blamed Ukrainian forces. An international investigation into the incident is ongoing.