The treaty is a post-Cold War defense accord that allows its signatories to carry out unarmed surveillance flights over each other’s territories. The treaty allowed its nearly three dozen signatories to carry out short-notice flights over one another’s territory to monitor potential military operations.

“The blame for what is happening — and this is a very unfortunate scenario — is entirely on the United States and NATO allies,” Kosachyov wrote.

Besides exiting from the Open Skies, Trump did the same with the Joint Comprehensive Plan of Action (JCPOA), commonly known as the Iran deal, and the Intermediate-Range Nuclear Forces (INF) Treaty.

Biden will have to face bilateral relations with Russia to negotiate the extension of the New START treaty, set to expire on February 5, and Washington’s last remaining arms reduction pact with Moscow.