On 4 October 2018 a meeting of the Nato Ministers of Defense was held in Brussels. Following this meeting, the NATO Secretary General Jens Stoltenberg mentioned that Russia may have violated the INF Treaty.
Signed in 1987, the Treaty on Nuclear Weapons of Intermediate Range (INF) should have put an end to the Cold War. Under the treaty, both the USSR and the USA undertook that at the same time they would destroy all their intermediate range nuclear weapons.
However in 2007, Russia declared that the Bouclier’s anti-missile weapons (Ground-Based Midcourse Defense) that the United States planned to install in Poland and Czechoslovakia breached the INF Treaty.
The Pentagon’s response: of course, some of the Bouclier’s anti-missile weapons are missiles but the requirement is, that they be deployed defensively. This requirement would take them outside the application of the INF Treaty.
Once the Pentagon implemented this programme, Russia considers that the treaty was meaningless and ceased to exist, even though neither party had taken any steps to declare it as such.
Moscow has just acknowledged that it will deploy the Buruvestnik 9m729 missiles. Noone knows much about these missiles other than that the Pentagon considers they violate the INF Treaty, the same treaty that the US is violating through its Bouclier programme. 
Valentin Vasilescu thinks that Russian had tested the missile fire of the nuclear cruise missiles, Burevestnik, from the MiG-3.