The United States told the Kremlin at a high level that any use of nuclear weapons would be disastrous for Russia.

U.S. National Security Adviser Jake Sullivan told CBS News that the United States and its allies will respond strongly.

The United States will continue to support Ukraine in its efforts to defend its country and its democracy.

“We have communicated directly, privately, at very high levels to the Kremlin, that any use of nuclear weapons will be met with catastrophic consequences for Russia, that the United States in our allies will respond decisively. And we have been clear and specific about what that will entail,” said the White House National Security Adviser.

Jake Sullivan noted that the United States does not recognize fictitious referendums in the occupied Ukrainian territory.

On the journalist’s remark that Vladimir Putin has never been as cornered as he is now, Sullivan said:

“It’s true, and it is a matter that we have to take deadly seriously because it is a matter of paramount seriousness – the possible use of nuclear weapons for the first time since the Second World War.”

According to U.S. intelligence, Russia has about 2,000 tactical nuclear weapons. Its tactical nuclear warheads can be deployed on different types of missiles, which are commonly used to deliver conventional explosives such as cruise missiles and artillery rounds.

Recently, Russian Foreign Minister Sergei Lavrov said that all Russian laws and doctrines, including nuclear, will apply to the territories of Ukraine annexed through illegal “referendums” if they are enshrined in the Constitution of Russia.

On September 21, Russian President Vladimir Putin, after announcing partial mobilization in the Russian Federation, again threatened Western countries with the use of nuclear weapons.

“In the event of a threat to the territorial integrity of our country, to protect Russia and our people, we will certainly use all the means at our disposal. It’s not a bluff,” he said in particular.

Putin’s decision came after a rapid Ukrainian counteroffensive, during which Ukraine liberated cities in the Kharkiv Region.