Former Soviet leader Mikhail Gorbachev slammed U.S. President Donald Trump’s plan to withdraw from a key anti-nuclear pact with Russia, calling the decision “not the work of a great mind.”

“All agreements aimed at nuclear disarmament and limiting nuclear weapons must be preserved, for the sake of preserving life on earth,” Gorbachev told Russia’s Interfax news agency Sunday.

Gorbachev, 87, negotiated the Intermediate-Range Nuclear Forces Treaty with then-President Ronald Reagan in 1987. It prohibits the U.S and Russia from possessing, producing or test-flying a ground-launched cruise missile with a range of 300 to 3,400 miles. Reagan hailed the treaty as a historic step toward world peace.

Trump announced Saturday that he plans to withdraw from the treaty because of unspecified violations by Russia.

“Russia has not, unfortunately, honored the agreement, so we’re going to terminate the agreement and we’re going to pull out,” Trump told reporters after a Nevada political rally. “We are going to terminate the agreement and then we are going to develop the weapons” unless Russia and China agree to a new deal, he added.

Gorbachev said he found Trump’s plan “very strange,” according to a translation of his comments to Interfax by CNBC. He wondered: “Do they really not understand in Washington what this can lead to?”

Gorbachev said such a move “will undermine all the efforts that were made by the leaders of the U.S.S.R. and the United States themselves to achieve nuclear disarmament.”

President Trump: "Russia has violated the agreement. They've been violating it for many years and I don't know why President Obama didn't negotiate or pull out." https://t.co/SZxlwMe8Kj pic.twitter.com/tpbR734Yw0 — The Hill (@thehill) October 21, 2018

Trump’s announcement has been criticized by Germany, as well as Democrats and some Republicans in the U.S.

Sen. Rand Paul (R-Ky.), who serves on the Foreign Relations Committee, called it a “big, big mistake to flippantly get out of this historic agreement” in an interview Sunday on Fox News. “We went from 64,000 nuclear-tipped missiles down to 15,000.”

He called Trump’s comments a reason why hawkish national security adviser John Bolton “shouldn’t be allowed anywhere near U.S. foreign policy.”

This is why John Bolton shouldn’t be allowed anywhere near US foreign policy. This would undo decades of bipartisan arms control dating from Reagan. We shouldn’t do it. We should seek to fix any problems with this treaty and move forward. https://t.co/xj5FqyCyS6 #FoxNews — Senator Rand Paul (@RandPaul) October 20, 2018

CORRECTION: A previous version of this story indicated Gorbachev had been the president of Russia instead of the Soviet Union.