The United States will respond decisively if Russia resorts to the use of nuclear weapons in Ukraine and the consequences for the Russian Federation will be catastrophic, US National Security Adviser Jake Sullivan said. "We have the opportunity to communicate directly with the Kremlin at a very high level and we have been clear and specific about what will entail,” Sullivan told NBC.

Washington sees that Russian leader Vladimir Putin wants to "wipe out" the Ukrainian people, and for that reason, Washington will continue to provide Kyiv with weapons, ammunition, intelligence and other assistance, Sullivan said.

"Anyone who has nuclear weapons should be taken seriously. Whether Putin is bluffing or not, we'll see. In my opinion, no nuclear weapons would be used in this situation. In order to make a decision for the use of a nuclear weapon, a special group is gathered and such a decision must be taken with complete unanimity", caretaker Minister of Defense Dimitar Stoyanov told "Nova TV".